Techniques and instruments for placement of orthopedic implants relative to bone features

ABSTRACT

Methods and instruments for placement of orthopedic implants in bones of a patient. The placement may include selective placement of the implant relative to structure of the bone using a measurement system that may detect interfaces between layers of the bone. The orthopedic implants may be engaged by various embodiments of chucks. The chucks may include structure for engaging indexing features of a corresponding orthopedic implant to restrict movement of the implant relative to the chuck along a working axis. The chucks may allow for use of an instrument having a measurement system for accurate and repeatable placement of the implants using the instrument.

RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 15/635,554, filed on Jun. 28, 2017, entitled “TECHNIQUES ANDINSTRUMENTS FOR PLACEMENT OF ORTHOPEDIC IMPLANTS RELATIVE TO BONEFEATURES”, which is a divisional application of U.S. application Ser.No. 15/336,202, filed on Oct. 27, 2016, entitled “TECHNIQUES ANDINSTRUMENTS FOR PLACEMENT OF ORTHOPEDIC IMPLANTS RELATIVE TO BONEFEATURES”, which claims the benefit of U.S. Provisional PatentApplication No. 62/247,022 filed Oct. 27, 2015, entitled “SYSTEM ANDMETHOD FOR PLACEMENT OF ORTHOPEDIC IMPLANTS RELATIVE TO BONE FEATURES,”which is incorporated herein by reference in its entirety.

FIELD

The present disclosure generally relates to the field of surgical tools,and specifically to surgical tools for use in placement of orthopedicimplants relative to the bone of a patient.

BACKGROUND

Often times it is necessary during orthopedic surgical operations toplace an implant relative to a bone of a patient. Such orthopedicimplants may include transcutaneous pins (e.g., intra medullary (IM)pins), wires (e.g., Kirschner wires (K-wires)), or other implants. Forinstance, such implants may be used for pin fixation of bones, inconnection with skeletal traction, or for other purposes. In any regard,placement of such implants may involve significant time, effort, andskill on the part of a surgeon.

For instance, depending upon the nature of the operation and/or purposeof the implant, it may be necessary to dispose the distal tip of theimplant at various locations relative to the structure of the bone ofthe patient. Furthermore, it may be necessary to create boxes or useother tools in connection with placement of an orthopedic implant. Indoing so, the surgeon is left to judge such placement based solely uponthe feel or perception of the surgeon. As the implants may be placedusing powered tools such as pneumatic or electric drills or the like,the placement of an implant often results in added time and complexityto an orthopedic operation. Moreover, as the surgeon's feel orperception is relied on for accurate placement, the potential exists forthe implant to be misplaced. Furthermore, having an implant passcompletely through the bone in which it is to be placed may also resultin damage to the issue surrounding the bone. In any event, the placementof orthopedic implants may present complications that may result inincreased time, cost, or risk to surgical procedures.

SUMMARY

In view of the foregoing, the present disclosure is generally directedto the use of an instrument having a measurement system to placeorthopedic implants with improved reliability and accuracy.Specifically, the measurement system may be operable to automaticallydetermine (e.g., based on one or more sensors of the measurement system)when the orthopedic implant (e.g., a leading edge thereof) passesthrough interfaces of various anatomical structures in a bone of thepatient. As such, an orthopedic implant may be placed based on thesensed position of the implant by the measurement system. Further still,in connection with the placement of a surgical instrument, othersurgical tools (e.g., drills, saws, grinders, etc.) may also be used bya surgeon to assist in the operation. Accordingly, the measurementsystem as described herein may also or alternatively be used todetermine the placement of a surgical tool (e.g., a drill, saw, burr,etc.) that may be used in an operation.

When using the instrument having a measurement system as describedherein, a surgeon may be able to rely on an automatically determinedposition of the orthopedic implant without having to rely on simply“sensing” or “feeling” the location of the implant relative to therelevant anatomical structures. As the sensitivities of the varioussensors of the instruments may be greater than that of the surgeon'ssenses alone, the position of an orthopedic implant may be moreaccurately and reliably placed relative to the anatomy of interest.Moreover, as use of a measurement system does not rely on a surgeon's“feel,” placement of the orthopedic implant may be more repeatable.

In an embodiment of a measurement system described herein, adisplacement sensor may be provided for use in determining the relativedisplacement of the orthopedic implant to a reference point. Forinstance, the reference point may be the exterior portion of the bone inwhich the implant is to be inserted. The displacement sensor may includea linear displacement sensor that is displaced relative to theorthopedic implant as the orthopedic implant is advanced into the boneof the patient. In this regard, it is advantageous to maintain theorthopedic implant stationary relative to the displacement sensoraxially in relation to the working axis of the orthopedic implant (i.e.,the axis about which the orthopedic implant is rotated and along whichthe orthopedic implant travels when advanced into the bone). That is, ifthe implant slips axially, the displacement measurement may beinaccurate. However, while the implant is to be maintained axiallystationary relative to the displacement sensor during advancement, thenature of orthopedic implants may result in the need to release theimplant from the instrument, retract of the instrument in a directionopposite the direction of advancement of the implant into the bone, andreengage the implant for further advancement. Also, the instrument maybe released to retract the instrument from the implant once placed inthe final position as desired.

Accordingly, the ability to selectively release the orthopedic implantfrom the instrument for retraction and/or reengagement may be provided.Such selective release of the orthopedic implant is preferably providedin an efficient and ergonomic manner as the operation of release and/orreengagement may occur frequently during an operation. As such, variouschuck embodiments are described herein that may be used to selectivelyengage an orthopedic implant for use with an instrument.

At least some embodiments described herein may allow for engagement inorthopedic implant by a chuck of instrument without requiring (i.e., inthe absence of) an external force be applied to the chuck by the user.For instance, many previously posed chucks used to engage orthopedicimplants required a user to continuously maintain a force on the chuck(e.g., a trigger lever thereof) to maintain engagement of the chuck withthe orthopedic implant. Such an arrangement that requires continuousapplication of an external force on the chuck by the user to maintainengagement of the orthopedic implant by the chuck may be disadvantageousin a number of ways. Initially, requiring a user to grasp and maintainan external force upon the chuck may diminish the user's ability toaccurately and precisely control the instrument. For example, a user maybe required to reach with the fingers of the hand used to grasp thehandle of the instrument to apply the force on the chuck to maintainengagement of the orthopedic implant with the chuck. In contrast, theembodiments described herein that may allow for engagement of the chuckin the absence of an applied external force by the user may allow theuser to more ergonomically grasp the handle of the instrument, thuspromoting increased control over the instrument.

Additionally, as may be particularly relevant in the context of use ofthe chuck with an instrument having a measurement system as describedherein, requiring the user to apply an external force to the chuckmaintain engagement with the orthopedic implant may provide inaccuraciesin relation to the measurement system. Initially, requiring a user tomaintain a force on the chuck to engage the orthopedic implant with thechuck may increase the likelihood that the orthopedic implant slips withrespect to the chuck. As may be appreciated, any such slippage betweenthe orthopedic implant in the chuck may be detected by the measurementsystem as movement of the orthopedic implant relative to the bone. Thatis, slippage between the orthopedic implants in the chuck may result ininaccuracies in relation to the displacement sensor output of themeasurement system described herein. However, utilization of a chuckthat does not require external force to be applied to the chuck tomaintain engagement with the orthopedic implant may reduce thepossibility that the orthopedic implant slips with respect to the chuckbecause the user is not required to actively engage with the chuck tomaintain engagement between the chuck and the orthopedic implant.

Further still, the measurement system described herein may utilize aforce sensor capable of measuring the axial force acting on theorthopedic implant by transmitting such force through the chuck and/ordrive system to a force sensor that is capable of measuring any suchaxial load. However, requiring a user to impart a force onto the chuckto maintain engagement between the chuck and the orthopedic implant mayintroduce erroneous forces acting on the chuck and/or drive system thatmay be detected by the force sensor and do not correspond to axial forceexperienced by the orthopedic implant as it is advanced relative to thebone of the patient. That is, the force imparted on the chuck by a userto maintain engagement between the chuck and the orthopedic implant mayresult in a noisy force signal that reduces the accuracy of themeasurement system. In turn, utilization of a chuck that does notrequire an external force be applied to the chuck to maintain engagementbetween the orthopedic implant and the chuck may improve the accuracy ofthe measurement system.

In at least certain embodiments described herein, a chuck may beprovided that allows for engagement of the orthopedic implant upon amotion of linear advancement of the orthopedic implant relative to thebone of the patient or upon a rotation of the chuck relative to theorthopedic implant. In this regard, upon advancement of the instrumentto advance the orthopedic implant relative to the bone of the patient,the chuck may engage the orthopedic implant to limit relative axialmovement between the orthopedic implant in the chuck that can bemeasured by the measurement system. However, retraction of the chuckrelative to the orthopedic implant may be allowed such that the chuckdisengages the orthopedic implant upon retraction of the chuck relativeto the orthopedic implant such that the instrument may be retracted fromthe orthopedic implant. Similarly, the chuck may engage the orthopedicimplant upon rotation of the chuck relative to the orthopedic implant(e.g., in a direction tending to drive the orthopedic implant into abone of a patient). However, upon counter rotation of the chuck relativeto the orthopedic implant, the orthopedic implant may be disengaged bythe chuck such that the instrument may be retracted relative to theorthopedic implant. Further still, such chuck embodiments may providevarious different states of engagement of the orthopedic implant. Forexample, the foregoing description of a particular advancement of thechuck relative to the orthopedic implant to cause engagement may beprovided in a biased state of the chuck. Furthermore, a locked openstate of the chuck may be provided whereby the orthopedic implant is notengaged by the chuck even upon advancement of the chuck relativelyorthopedic implant in a manner that would otherwise engage theorthopedic implant when the chuck is in the biased state of the chuck.Additionally, a locked closed state of the chuck may be provided wherebythe orthopedic implant may be engaged regardless of whether the chuck isadvanced or retracted and/or regardless of how the chuck is rotatedrelative to the orthopedic implant.

In one particular embodiment, the chuck and orthopedic implant may becoordinately provided such that the chuck may engage one or more of aplurality of indexing features provided on the orthopedic implant. Inthis regard, the orthopedic implant may be engaged at known relativepositions along the orthopedic implant relative to (e.g., along) theworking axis. This may assist in determining the distance that theorthopedic implant has been advanced into the bone of the patient. Thecoordinated engagement between a chuck and one or more of the pluralityof indexing members may also help to reduce the potential for axialslipping of the orthopedic implant relative to the chuck as the implantis advanced. Notably, the engagement may maintain the orthopedic implantin an axial position relative to the displacement sensor without thepresence of external forces acting on the chuck to maintain the implantin place. For instance, in contrast to prior proposed chuck designs thatrely on a user gripping a lever or otherwise actuating the chuck tomaintain the engagement with the orthopedic implant, the use of a chuckas described herein that engages an indexing portion may alleviate theneed for such user intervention to maintain external forces acting onthe chuck to maintain engagement with the orthopedic implant. This mayalso allow for improved accuracy in measurement of forces acting axiallyon the orthopedic implant.

In certain embodiments described herein, a chuck may also be providedwith an implant holder to reduce axial and/or rotational movement of theorthopedic implant relative to the chuck when the orthopedic implant isnot engaged with the chuck jaws. For example, there may be instanceswhen the chuck jaws will not be engaged with the orthopedic implant, butit may still be desired that the orthopedic implant not slide or rotateabout the working axis (e.g., to prevent the orthopedic implant fromslipping under the influence of gravity). For instance, upon initialintroduction of the orthopedic implant relative to the chuck, the usermay desire the orthopedic implant to remain stationary absent anapplication of an external force to the orthopedic implant prevent theorthopedic implant from sliding from the instrument (e.g., under theinfluence of gravity). In this context leading up to engagement by thechuck jaws of the orthopedic implant for use in a procedure, a surgeonmay want the ability to adjust the orthopedic implant from a firstposition to a second position and/or have the orthopedic implant remainin place when the instrument is moved. As such, the implant holder mayhelp prevent axial slipping of the orthopedic implant relative to thechuck during use without the presence of any additional external forcesacting on the orthopedic implant. Specifically, when the orthopedicimplant is disposed within a chuck, grippers of the implant holder mayengage the orthopedic implant, allowing secure one-handed use of theinstrument such that the orthopedic implant is retained in place absentan external force beyond a certain, predetermined magnitude beingapplied. In this regard, a force by the surgeon to move the orthopedicimplant along or about the axis may be facilitated. However, absentapplication of such an external force (e.g., by the surgeon), theorthopedic implant may remain stationary.

Furthermore, while the instrument having a measurement system asdescribed herein may provide advantages over placing an orthopedicimplant in a bone without use of the measurement system, certainoperations and/or user preference may result in the instrument beingused in a traditional sense without the measurement system. In thisregard, the present disclosure also describes chuck embodiments that mayengage a traditional orthopedic implant such that the instrument may beoperated without the assistance of the measurement system. These chuckembodiments may also include features that allow for management (e.g.,retention) of the measurement system components when used in thistraditional manner.

Utilization of the measurement system in conjunction with placement ofthe orthopedic implant may allow for the orthopedic implant to belocated precisely relative to the bone of the patient. When placing anorthopedic implant, the exact placement of the distal portion of theimplant may vary from procedure to procedure. For example, the placementof the orthopedic implant may vary based upon the bone into which theorthopedic implant placed, the nature of the procedure relative to thebone, the nature of the repair of the bone, the use of the orthopedicimplant, or other relevant factors that may dictate the placement of theorthopedic implant. Accordingly, while the measurement system mayprovide for precise determination of the location of the orthopedicimplant as it is advanced into the bone of the patient, it may benecessary to provide various modes of operation for selective placementof the orthopedic implant as desired for a given specific procedure on agiven specific portion of anatomy. As such, embodiments of theinstrument described herein may include a mode selection that allows theuser to select a particular mode of operation for specific placement ofthe orthopedic implant. Specifically, various modes of operationincluding a bicortical, subchondral, endosteal, and multi-cortical modeswill be described herein.

In turn, the sensors of the measurement system may be interrogated andanalyzed to determine placement of the orthopedic implant. Variousapproaches to this analysis may be provided. For example, differentanalysis techniques may be used for different given ones of theplacement modes. The analysis techniques may include coordinated orcollective analysis of a displacement sensor signal and a force sensorsignal. Other techniques may include analysis of a single given sensoroutput of the measurement system. For instance, a displacement sensor oraccelerometer may be used singularly for analysis in connection withplacement of the implant. In either instance, additional signals may bederived from the single sensor. For instance, a displacement, velocity,acceleration, and/or derivative signal may be derived from the singlesensor employed. These values may be used individually or collectivelyto determine placement of the implant in the bone. Such placementdeterminations may also be used to assist in the determining a locationof a tool (e.g., a drill, saw, grinder, or the like) relative to thestructure of a bone.

Further still, specific embodiments of orthopedic implants are describedherein that may be utilized to provide improved performance whenintroduced into the bone of the patient using an instrument having ameasurement system as described herein. For instance, determinationusing the measurement system of the placement of very small diameterorthopedic implants and/or orthopedic implants that are advancedrelatively slowly into the bone of the patient may be difficult todetermine. In this regard, specific embodiment of an orthopedic implantthat may be utilized to provide improved performance when utilized withthe measurement system. Specifically, the orthopedic implant may includea tapered or conical distal end of the orthopedic implant that isrelatively blunt. A relief portion may be provided proximal to therelatively blunt distal end of the orthopedic implant that may provide arelief to reduce heat near the distal end of the orthopedic implantand/or reduce tissue damage in the area proximal to the distal end ofthe orthopedic implant. Further still, a helical section may be providedproximally to the distal end of the orthopedic implant and/or the reliefportion that may be utilized to engage a cortex of the bone to assist inadvancement of the orthopedic implant relative to the bone.

Accordingly, a first aspect of the present invention comprises asurgical instrument for use in placement of orthopedic implants relativeto a bone of a patient. The instrument includes an instrument bodyhaving a first cannulated passage extending continuously through theinstrument body along a working axis of the instrument. The firstcannulated passage is sized to receive and extend about at least aportion of an orthopedic implant within the cannulated passage. Theinstrument also includes a chuck engageable with the orthopedic implantto selectively engage the orthopedic implant to restrict axial movementof the orthopedic implant relative to the chuck along the working axisin the absence of an external force being applied to the chuck. Thechuck includes a second cannulated passage axially aligned along theworking axis. The instrument also includes a drive engaged with thechuck to impart rotational motion of the chuck about the working axis.The instrument also includes a measurement system having a displacementsensing arm moveable in a direction parallel to the working axis tomeasure advancement of the orthopedic implant driven by the instrumentinto the bone of the patient along the working axis.

A number of feature refinements and additional features are applicableto the first aspect. These feature refinements and additional featuresmay be used individually or in any combination. As such, each of thefollowing features that will be discussed may be, but are not requiredto be, used with any other feature or combination of features of thefirst aspect.

For example, in certain embodiments, the chuck may be normally biasedinto engagement with the orthopedic implant. The chuck may include aplurality of jaw members that are engaged by a cam surface biased intoengagement with the plurality of jaw members to dispose the jaw memberstoward the working axis to engage the orthopedic implant.

In an embodiment, a linear motion of advancement of the chuck relativeto the orthopedic implant urges the plurality of jaw members of thechuck into engagement with the orthopedic implant. In this embodiment,the cam surface may include an annular ramped surface that is biasedinto engagement with the plurality of jaw members. Each of the pluralityof jaw members may be a roller member engaged with the annular rampedsurface such that at least a portion of each of the roller members atleast partially extends into the second cannulated passage to engage theorthopedic implant. The roller member may be disposed for pivotalmovement about a pivotal axis that is orthogonal to and offset from theworking axis, and wherein the pivotal axis is eccentric to the rollermember. In turn, the linear motion of advancement of the chuck relativeto the orthopedic implant causes rotation of the roller member about thepivotal axis such that the roller member is moved toward the workingaxis, and such movement of each of the plurality of roller members maycreate a clamping engagement of the orthopedic implant by the pluralityof roller members upon the linear motion of advancement of the chuckrelative to the orthopedic implant. In contrast, motion of the chuckopposite the linear motion of advancement may cause counter rotation ofthe roller member about the pivotal axis such that the roller member ismoved away from the working axis, thus allowing the orthopedic implantto move relative to the roller member when the chuck is moved oppositethe linear motion of advancement to allow for retraction of the chuckrelative to the orthopedic implant.

In an alternate embodiment, a rotational motion of the chuck relative tothe orthopedic implant may urge the plurality of jaw members of thechuck into engagement with the orthopedic implant. In this embodiment,the cam surface comprises a helical surface that engages the pluralityof jaw members. Each of the plurality of jaw members comprise aspherical member engaged with the helical surface such that at least aportion of each of the spherical members at least partially extends intothe second cannulated passage to engage the orthopedic implant. A twistof the helical surface may urge each of the spherical members toward theworking axis when rotated in a direction corresponding with advancementof the orthopedic implant.

In these embodiments, the cam surface may be engaged with a controlmember to dispose the cam surface between a biased state, a locked-openstate, and a locked-close state. When in the biased state, the camsurface may urge the plurality of jaw members into engagement with theorthopedic implant at least upon a motion of advancement of the chuckrelative to the orthopedic implant. Additionally, when in the lockedclosed state, the cam surface may engage the orthopedic implant upon amotion of advancement or retraction. Further still, when in the lockedopen state, the cam surface may dispose the plurality of jaw members toallow movement of the orthopedic implant axially along the working axisrelative to the chuck.

In certain contexts described herein, the orthopedic implant may beselected from the group consisting of a transcutaneous pin and aKirschner wire. However, the disclosure presented herein may beapplicable to any orthopedic implant and/or surgical tool that may beengaged with an instrument such as a drill, saw, grinder, or the like.

In an embodiment, the chuck may be operative to engage a plurality ofindexing features at predefined axial increments along the orthopedicimplant. The chuck may include at least one jaw member displaceablerelative to the second cannulated passage to selectively engage anddisengage at least one of the plurality of indexing features of theorthopedic implant. The chuck may include a first jaw member and asecond jaw member arranged for opposing engagement of the orthopedicimplant in a radial direction relative to the working axis. The firstjaw member may be offset from the second jaw member relative to theworking axis. Specifically, the first jaw member may be offset from thesecond jaw member relative to the working axis a distance less than alength of the engagement feature along the working axis.

In one application, the first jaw member may be pivotal relative to afirst pivot axis and the second jaw member may be pivotal relative to asecond pivot axis. The first pivot axis and the second pivot axis may beparallel to and offset from the working axis such that relative pivotalmovement between the first jaw member and the second jaw member aboutthe first pivot axis and the second pivot axis, respectively, results inthe opposing radial movement of the first jaw member and the second jawmember relative to the working axis. In turn, the chuck may include acontrol ring disposed at an exterior surface of the chuck that ismanipulable by a user to induce the relative pivotal movement of thefirst jaw member and the second jaw member. The control ring may includea first cam surface and a second cam surface. The first jaw member mayinclude a first follower portion engaged with the first cam surface andthe second jaw member may include a second follower portion engaged withthe second cam surface. As such, upon rotation of the control ring by auser, the first cam surface and the second cam surfaces may bear on thefirst follower portion and the second follower portion to move the firstjaw member and the second jaw member away from the working axis in adirection radial to the working axis. The first jaw member and thesecond jaw member may be biased into an engaged position where the firstjaw member and the second jaw member may be biased in a directionradially toward the working axis.

In an embodiment, the chuck may also include at least one implant holderdisplaceable relative to the second cannulated passage to retain theorthopedic implant. The implant holder may include at least one gripperand a spring. The spring may bias the at least one gripper toward theworking axis in a direction radial to the working axis. In turn, uponinsertion of the orthopedic implant, the orthopedic implant may displacethe gripper away from the working axis in a direction radial to theworking axis and the implant holder bears on the orthopedic implant in adirection radially toward the working axis.

A second aspect presented herein includes a system for use with asurgical instrument for placement of orthopedic implants. The systemincludes an orthopedic implant having a plurality indexing featuresprovided at predefined axial increments along the orthopedic implant anda chuck engageable with at least one of the plurality of indexingfeatures to restrict axial movement of the orthopedic implant relativeto the chuck along a working axis of the chuck.

A number of feature refinements and additional features are applicableto second aspect. These feature refinements and additional features maybe used individually or in any combination. As such, each of thefollowing features that will be discussed may be, but are not requiredto be, used with any other feature or combination of features of thesecond aspect. Furthermore, any of the features described in relation tothe first aspect may be used with the second aspect.

In an embodiment of the second aspect, the orthopedic implant mayinclude a cylindrical body extending from a proximal portion engageablewith a bone of a patient to a distal portion opposite the proximalportion. The orthopedic implant may be selected from the groupconsisting of a transcutaneous pin and a Kirschner wire. The chuck mayinclude at least one jaw member displaceable relative to the secondcannulated passage to selectively engage and disengage at least one ofthe plurality of indexing features of the orthopedic implant. Theplurality of indexing features may include indented portions of thecylindrical body extending radially toward a center axis of thecylindrical body. The indented portions may extend along opposing sidesof the orthopedic implant.

In an embodiment, the indented portions may be offset a first distancealong the working axis relative to the opposing sides. The chuck mayinclude a first jaw member and a second jaw member arranged for opposingengagement of the orthopedic implant in a radial direction relative tothe working axis. The first jaw member may be offset a second distancefrom the second jaw member relative to the working axis such that thesecond distance corresponds with the first distance. The first jawmember may be offset from the second jaw member relative to the workingaxis a distance less than a length of the engagement feature along theworking axis. The first jaw member may be pivotal relative to a firstpivot axis and the second jaw member may be pivotal relative to a secondpivot axis. The first pivot axis and the second pivot axis may beparallel to and offset from the working axis such that relative pivotalmovement between the first jaw member and the second jaw member aboutthe first pivot axis and the second pivot axis, respectively, results inthe opposing radial movement of the first jaw member and the second jawmember relative to the working axis.

The chuck may include a control ring disposed at an exterior surface ofthe chuck that is manipulable by a user to induce the relative pivotalmovement of the first jaw member and the second jaw member. The controlring may include a first cam surface and a second cam surface. The firstjaw member may include a first follower portion engaged with the firstcam surface and the second jaw member may include a second followerportion engaged with the second cam surface. Upon rotation of thecontrol ring by a user, the first cam surface and the second camsurfaces bear on the first follower portion and the second followerportion to move the first jaw member and the second jaw member away fromthe working axis in a direction radial to the working axis. The firstjaw member and the second jaw member may be biased into an engagedposition where the first jaw member and the second jaw member are biasedin a direction radially toward the working axis.

A third aspect includes an orthopedic implant for use in conjunctionwith a measurement system of an instrument for advancing the orthopedicimplant into a bone of a patient. The orthopedic implant includes adistal end comprising a working portion rotatably advanceable relativeto the bone of the patient. The implant also includes a cylindrical bodyextending proximally from the distal end and a plurality of indexingfeatures at predefined axial increments along the cylindrical body ofthe orthopedic implant that are engageable by a chuck of the instrumentto restrict axial movement of the orthopedic implant relative to thechuck along a working axis of the chuck.

A number of feature refinements and additional features are applicableto the third aspect. These feature refinements and additional featuresmay be used individually or in any combination. As such, each of thefollowing features that will be discussed may be, but are not requiredto be, used with any other feature or combination of features of thethird aspect.

For instance, the indexing features may include indented portions of thecylindrical body extending radially toward a center axis of thecylindrical body. The indented portions may extend along opposing sidesof the orthopedic implant. The indented portions may be offset a firstdistance along the working axis relative to the opposing sides.

A fourth aspect includes a method of advancing an orthopedic implantinto a bone of a patient. The method includes engaging the orthopedicimplant with a chuck of an instrument to restrict axial movement of theorthopedic implant relative to the chuck along a working axis of thechuck. The method further includes first advancing the orthopedicimplant distally into the bone of the patient a first distance byimparting rotational motion to the chuck when engaged with theorthopedic implant and first measuring the first distance using adisplacement sensor of a measurement system associated with theinstrument. The method also includes releasing the orthopedic implantfrom the chuck and retracting the instrument relative to the orthopedicimplant in a proximal direction opposite of the direction of theadvancing. The method includes reengaging the orthopedic implant withthe chuck of the instrument to restrict axial movement of the orthopedicimplant relative to the chuck along a working axis of the chuck andsecond advancing the orthopedic implant distally into the bone of thepatient a second distance by imparting rotational motion to the chuck.The method includes second measuring the second distance using thedisplacement sensor of the measurement system associated with theinstrument.

A number of feature refinements and additional features are applicableto the fourth aspect. These feature refinements and additional featuresmay be used individually or in any combination. As such, each of thefollowing features that will be discussed may be, but are not requiredto be, used with any other feature or combination of features of thefourth aspect.

For instance, in an embodiment, the method may include summing the firstdistance and the second distance at the measurement system. Furthermore,the method may include determining that the orthopedic implant isreleased from the chuck and disregarding any change in displacement ofthe displacement sensor when the orthopedic implant is released from thechuck. A sensor may be provided relative to the chuck to determine thatthe orthopedic implant is released from the chuck. The determining mayalternatively be based on a user input provided to the measurementsystem. The engaging may include the chuck engaging the orthopedicimplant at a first indexing feature of a plurality of indexing featuresand the reengaging comprises the chuck engaging the orthopedic implantat a second indexing feature of the plurality of indexing features thatis proximal to the first indexing feature. The engaging may occur inresponse to the first advancing, the reengaging may occur in response tothe second advancing, and the releasing may occur in response to theretracting.

A fifth aspect includes a method of placement of an orthopedic implantrelative to a bone of a patient. The method includes engaging theorthopedic implant with a chuck of an instrument to restrict axialmovement of the orthopedic implant relative to the chuck along a workingaxis of the chuck and advancing the orthopedic implant distally into thebone of the patient while the orthopedic implant is engaged with thechuck by imparting rotational motion to the chuck with a drive engagedwith the chuck. The method also includes measuring at least onecharacteristic of the advancement of the orthopedic implant relative tothe bone. The method further includes continuously monitoring the atleast one characteristic during the advancing to determine apredetermined placement of a distal end of the orthopedic implant anddeactivating the drive to cease rotation of the chuck to stop theadvancement of the orthopedic implant when the distal end of theorthopedic implant reaches the predetermined placement as determined bythe continually monitored at least one characteristic. The predeterminedplacement is selectable by a user from a bicortical mode, a subchondralmode, an endosteal mode, and a multi-cortical mode.

A number of feature refinements and additional features are applicableto the fifth aspect. These feature refinements and additional featuresmay be used individually or in any combination. As such, each of thefollowing features that will be discussed may be, but are not requiredto be, used with any other feature or combination of features of thefifth aspect.

For instance, the at least one characteristic may include a force actingaxially on the orthopedic implant and a depth of penetration of theorthopedic implant. Additionally or alternatively, the at least onecharacteristic may include a depth of penetration of the orthopedicimplant as determined by a displacement sensor that generates adisplacement signal. The displacement signal may also or alternativelybe used to generate a velocity signal and an acceleration signal. Inthis regard, the predetermined placement may be determined based on thedisplacement signal, the velocity signal, and the acceleration signal.The displacement signal may be used to generate a derivative signalcomprising a derivative of an acceleration signal generated using thedisplacement signal. The derivative signal is used to determine thepredetermined placement. An inflection point of the derivative signalmay correspond to an interface between a first medium having a firstdensity and a second medium having a second density. Specifically, aconcave up inflection point is indicative of the orthopedic implantpassing through the interface where the first density is less than thesecond density. In contrast, a concave down inflection point isindicative of the orthopedic implant passing through the interface wherethe first density is greater than the second density.

A sixth aspect includes an orthopedic implant. The implant includes acylindrical body extending between a distal end and a proximal end. Theimplant also includes a tapered portion adjacent to the distal end thatis advanceable relative to a bone of the patient. The implant furtherincludes a relief portion proximal to the distal end extending about thecylindrical body and a helical portion proximal to the relief portion.

A number of feature refinements and additional features are applicableto the sixth aspect. These feature refinements and additional featuresmay be used individually or in any combination. As such, each of thefollowing features that will be discussed may be, but are not requiredto be, used with any other feature or combination of features of thesixth aspect.

For instance, in an embodiment, the helical portion may include threadsto engage a cortex of a bone. The relief portion may include acircumferentially extending step having a first radius that is smallerthan a second radius of the cylindrical body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of an instrument that may be used inconnection with placement of an orthopedic implant.

FIG. 2 depicts a cross sectional view of an embodiment of an instrumentwith an orthopedic implant engaged therewith.

FIG. 3 depicts a cross sectional view of an embodiment of an instrumentthat may be used with an orthopedic implant.

FIG. 4 depicts a partial cutaway view of an embodiment of a distalportion of an instrument for engagement with an interchangeable chuck.

FIG. 5 depicts an embodiment of a chuck for engagement with aninstrument.

FIG. 6A depicts a cross sectional view of an embodiment of an instrumentand interchangeable chuck as assembled.

FIG. 6B depicts a detail view of the embodiment depicted in FIG. 6A atan interface of the chuck with the instrument.

FIG. 7 depicts an embodiment of a chuck that may be used to retain anorthopedic implant.

FIG. 8 depicts the embodiment of the chuck of FIG. 7 with an exteriorportion thereof not shown for clarity.

FIG. 9 depicts the embodiment of the chuck of FIG. 7 in cross sectionalong a working axis of the chuck.

FIG. 10 depicts an embodiment of a chuck that may be used to retain anorthopedic implant.

FIG. 11 depicts a cross sectional view of the chuck of FIG. 10 along aworking axis of the chuck.

FIG. 12 depicts an embodiment of a chuck that may be used to retain anorthopedic implant.

FIG. 13 depicts a cross sectional view of the chuck of FIG. 12 along aworking axis of the chuck.

FIGS. 14A and 14B depict an embodiment of a chuck that may be used toretain an orthopedic implant that is shown in cross section along aworking axis of the chuck.

FIG. 15 depicts an exploded view of the chuck of FIG. 14.

FIG. 16 depicts an embodiment of a chuck with a displacement sensing armretention member for retaining a displacement sensing arm of aninstrument with which the chuck is engaged where the displacementsending arm retention member is in an engaged position.

FIG. 17 depicts an embodiment of a chuck with a displacement sensing armretention member for retaining a displacement sensing arm of aninstrument with which the chuck is engaged where the displacementsending arm retention member is in a disengaged position.

FIG. 18 depicts an embodiment of an orthopedic implant having indexingfeatures.

FIG. 19 depicts an embodiment of an orthopedic implant having indexingfeatures.

FIG. 19A depicts a detail of the embodiment of the orthopedic implant ofFIG. 19.

FIG. 20 depicts an embodiment of an orthopedic implant having indexingfeatures.

FIG. 21 depicts an embodiment of a chuck adapted for engagement of anorthopedic implant having indexing features.

FIG. 22 depicts the embodiment of the chuck of FIG. 21 with a distalplate thereof removed for purposes of illustration of jaw membersdisposed therein.

FIG. 23 depicts the embodiment of the chuck of FIG. 21 in cross sectionalong a working axis of the chuck.

FIG. 24 depicts the embodiment of the chuck of FIG. 21 with a distalplate thereof removed to show positioning of the orthopedic implantrelative to the chuck for purposes of illustration of jaw membersdisposed therein.

FIG. 25 depicts the embodiment of the chuck of FIG. 21 in cross sectionalong a working axis thereof with an orthopedic implant placed relativeto the chuck.

FIG. 26 depicts the embodiment of the chuck of FIG. 21 with a distalplate thereof removed to show an orthopedic implant engaged with jawmembers of the chuck.

FIG. 27 depicts the embodiment of the chuck of FIG. 21 in cross sectionalong a working axis thereof with an orthopedic implant engaged with thechuck.

FIG. 28 depicts a side view of the embodiment of the chuck of FIG. 21.

FIG. 29 depicts a front view of the embodiment of FIG. 21 in crosssection along line A-A of FIG. 28.

FIG. 30 depicts a front view of the embodiment of FIG. 21 in crosssection along line B-B of FIG. 28.

FIG. 31 depicts an embodiment of a chuck adapted for engagement of anorthopedic implant having indexing features.

FIG. 32 depicts the embodiment of the chuck of FIG. 31 in cross sectionalong a working axis thereof.

FIG. 33 depicts a rear perspective view of the embodiment of the chuckof FIG. 31.

FIG. 34 depicts an exploded view of selected portions of the embodimentof the chuck of FIG. 31.

FIG. 35 depicts a cross sectional view of an engagement control memberrelative to a control ring in the embodiment of the chuck of FIG. 31.

FIGS. 36A and 36B depict an embodiment of a controller for use with aninstrument.

FIG. 37 depicts a cross sectional view of a bone with an orthopedicimplant placed using a bicortical mode of operation of an instrument.

FIG. 38 depicts a cross sectional view of a bone with an orthopedicimplant placed using a subchondral mode of operation of an instrument.

FIG. 39 depicts a cross sectional view of a bone with an orthopedicimplant placed using an endosteal mode of operation of an instrument.

FIG. 40 depicts a cross sectional view of a plurality of bones with anorthopedic implant placed using a multi-cortical mode of operation of aninstrument.

FIGS. 41 and 42 depict a plot of various signals measured or derived inan embodiment of operation of the instrument that include a change inforce measure as measured by a force sensor of the measurement system.

FIGS. 43 and 44 depict a plot of various signals including a derivativesignal derived in an embodiment of an operation of the instrument thatare derived from a single sensor.

FIG. 45 depicts an embodiment of a chuck in cross section along theworking axis thereof that includes an implant holder utilized tomaintain the position of the orthopedic implant and a second cannulatedpassage of the chuck even when the chuck jaws are not engaged with theorthopedic implant.

FIG. 46 depicts the implant holder of the embodiment of the chuck ofFIG. 45 in cross section perpendicular to a working axis of the chuck.

FIGS. 47-49 depict the distal end of embodiment of an orthopedic implantthat may be utilized in connection with an instrument as describedherein.

FIG. 50 depicts an embodiment of a chuck.

FIG. 51 depicts the embodiment of the chuck of FIG. 50 in across-sectional view taken along the working axis of the chuck.

FIG. 52 depicts an orthopedic implant engagement portion of theembodiment of the chuck of FIG. 50 in isolation.

FIG. 53 depicts the implant engagement portion of FIG. 52 in crosssection along the working axis of the chuck.

FIG. 54 depicts the implant engagement portion of FIG. 52 and a rearperspective view depicting engagement of the jaw members with an arcuateramp surface.

FIGS. 55-56 depict the chuck of FIG. 50 with portions thereof shown inphantom to illustrate utilization of a control ring of the chuck fordisposing the chuck between various states of engagement of theorthopedic implant.

FIG. 57 depicts an embodiment of a chuck.

FIG. 58 depicts the embodiment of the chuck of FIG. 57 in across-sectional view taken along the working axis of the chuck.

FIG. 59 depicts an orthopedic implant engagement portion of theembodiment of the chuck of FIG. 57 in isolation.

FIG. 60 depicts the orthopedic implant engagement portion of theembodiment of the chuck of FIG. 57 in a cross-sectional view taken alongthe working axis of the chuck.

FIGS. 61-62 depicts the orthopedic implant engagement portion of theembodiment of the chuck of FIG. 57 with a ramp member thereof not shownfor clarity.

FIG. 63 depicts the orthopedic implant engagement portion of theembodiment of the chuck of FIG. 57 and cross-sectional view taken alongthe working axis of the chuck.

FIGS. 64-66 depict the chuck of FIG. 57 with portions thereof shown inphantom to illustrate utilization of a control ring of the chuck fordisposing the chuck between various states of engagement of theorthopedic implant.

DETAILED DESCRIPTION

The following description is not intended to limit the invention to theforms disclosed herein. Consequently, variations and modificationscommensurate with the following teachings, skill and knowledge of therelevant art, are within the scope of the present invention. Theembodiments described herein are further intended to explain modes knownof practicing the invention and to enable others skilled in the art toutilize the invention in such, or other embodiments and with variousmodifications required by the particular applications(s) or use(s) ofthe present invention.

As described above, the present disclosure includes disclosure thatrelates to the use of an instrument having a measurement system forplacement of an orthopedic implant into the anatomy (e.g., the bone) ofa patient. For instance, the orthopedic implant may include a pin orwire that is placed in the bone of the patient using a poweredinstrument such as a drill or the like. FIGS. 1-3 depict an embodimentof an instrument 10 that may be utilized for such placement of anorthopedic implant 62.

The use of orthopedic implants such as pins (e.g., IM pins) and/or wires(e.g., K-wires) may be used in a variety of orthopedic applications. Theorthopedic implants may be used to provide traction to the bones of apatient. Moreover, the orthopedic implant may be placed to allow forinduced motion of a bone (e.g., to provide alignment, rotation, or othermanipulation of a bone). Furthermore, orthopedic implants may be usedfor fixation to secure fractured bone portions. In any regard, for thevarious contexts of uses for the orthopedic implants, different relativeplacements may be desired. Such placement may be aided by use of ameasurement system that may assist in determining placement of theorthopedic implant as described in detail below.

As will be described in greater detail below, use of an instrumenthaving a measurement system may provide a number of benefits in relationto placement of an orthopedic implant. For instance, because themeasurement system may have the capability of automatically detectingwhen an implant passes through an interface of the bone, the user of theinstrument may not be required to determine implant placement by “feel”alone. In turn, the time required to place an implant may be reduced.Moreover, the repeatability of implant placement may be increased.Moreover, embodiments are described herein wherein a user may not berequired to impart an external force onto a chuck to maintain engagementwith an orthopedic implant. In turn, the user may be more able tocontrol the instrument as a more ergonomic grip with greater control ofthe instrument may be taken by the user. Further still, by not requiringan external force be applied to the chuck for engagement of theinstrument, the measurement system may provide increased accuracy bothbased on a reduced potential that the orthopedic implant slips relativeto the instrument and/or based on a more accurate force signal that maynot be subject to noise in the form of erroneous forces resulting fromengagement with the chuck by the user.

Further still, when utilizing a measurement system for placement of anorthopedic implant, it may be advantageous to periodically disengage theorthopedic implant from the instrument so as to allow the instrument tobe moved relative to the orthopedic implant. For example, the orthopedicimplant may be advanced a certain distance into the bone of the patient.The advancement of the orthopedic implant may be greater than thedistance that is measurable by a single stroke of the displacementsensing arm of the measurement system. As such, the instrument may bedisengaged and moved distally relative to the orthopedic implant. Theinstrument may thereafter reengage the orthopedic implant for continuedadvancement of the orthopedic implant. In this regard, it may beadvantageous to provide efficient engagement and disengagement of theorthopedic implant without requiring external force be applied by theuser and while maintaining the orthopedic implant stationary along theworking axis. Accordingly, at least some of the embodiments describedherein may allow for efficient retraction of the instrument relative tothe implant. Such retraction may include disengagement of the chuck fromthe implant in an ergonomic and efficient manner. Still otherembodiments allow for engagement of the implant upon advancementthereof, while allowing for disengagement (e.g., automatically) when theinstrument in retracted relative to the implant.

The instrument 10 may include a chuck 20 for engagement of an orthopedicimplant 62. The orthopedic implant 62 may comprise a portion of anorthopedic implant assembly 60 that may be specifically adapted forutilization with the measurement system 40 of the instrument 10. Forinstance, the assembly 60 may include the implant 62 and acorrespondingly sized bushing 64 as will be described in greater detailbelow.

A drive system 30 may be provided that may include a motor 32 and agearbox 34. In turn, the drive system 30 may engage the chuck 20 toimpart rotational motion to the chuck 20 about a working axis 16. Thatis, the working axis 16 may define an axis of rotation about which thedrive system 30 may induce rotation of the chuck 20 and, when engagedtherewith, an orthopedic implant 62. In this regard, the orthopedicimplant 62 may be advanced into a bone along the working axis 16.Notably, the chuck 20 and drive system 30 maybe cannulated to accept theorthopedic implant 62. Furthermore, the drill housing 12 may also becannulated such that the orthopedic implant 62 may pass entirely throughthe body the instrument 10 including the chuck 20, drive system 30, andhousing 12. In this regard, the instrument 10 may include a cannulatedpassage 76 may extend from the proximal portion of the instrument 10 toa distal portion thereof. This cannulated passage may be defined, atleast in part, by the chuck 20, the drive system 30, and the housing 12.As such, the chuck 20 may also include a cannulated passage 22. In thisregard and as will be described in greater detail below, the cannulatedpassage 22 of the chuck 20 may be selectively aligned to the cannulatedpassage 76 of the instrument 10 in embodiments where the chuck 20selectively removable from the instrument 10 for interchanging of thechuck utilized with the instrument 10.

With continued reference to FIGS. 1-3, an embodiment of a measurementsystem 40 is shown. The instrument 10 may be adapted for use with anorthopedic implant assembly 60 that may include a bushing 64. Thebushing 64 may be correspondingly sized to extend about at least aportion of the orthopedic implant 62 to allow for constrained axialmovement of the bushing 64 relative to the orthopedic implant 62.Alternatively, the bushing 64 may be integrally provided with themeasurement system 40 as described in greater detail below. Theinstrument 10 may comprise at least some components of the measurementsystem 40 within the housing 12 to facilitate operation of themeasurement system 40 in connection with the instrument 10. For example,at least a portion of a displacement sensor 42 may be integrated into ahousing 12 of the instrument 10. In this regard, the displacement sensor42 may include a depth sensing arm 44 that is specifically adapted forengagement with the bushing 64 of the orthopedic implant assembly 60that may be engaged by a chuck 20 of the instrument 10. While thebushing 64 is shown as a discrete part, the bushing 64 may also beprovided integrally with the displacement sensing arm 44.

The measurement system 40 may also include a force sensor 50. The forcesensor 50 may be disposed relative to the drive system 30. The chuck 20and drive system 30 may undergo relative movement to the force sensor50. However, the chuck 20 and drive system 30 may be axially rigid suchthat an axial force acting on the chuck 20 (e.g., as imparted to theimplant 62 upon axial advancement of the orthopedic implant 62 engagedwith the chuck 20) may be passed to the chuck 20 and drive system 30such that the drive system 30 may impinge on the force sensor 50 suchthat the force sensor 50 may measure the force. Thus, the chuck 20 anddrive system 30 may be supported such that the axial movement of thechuck 20 and drive system 30 is limited (e.g., to prevent error inrelation to the displacement sensor 42), yet allow for the free transferof force to the force sensor 50. That is, it is advantageous to reducethe action of errant forces on the chuck 20 and drive system 30 alongthe working axis 16 to improve the accuracy of the measured force at theforce sensor 50. For instance, upon contact of the drive system 30 withthe force sensor 50, further axial forces on the drive system 30 mayresult in minimal deflection (i.e., imperceptibly by the displacementsensor 40) while impinging on the force sensor 50. In this regard, thedrive system 30 may be constrained for contacting engagement with theforce sensor 50, but otherwise free to deflect along the working axis toachieve an accurate force measurement. As will be appreciated in greaterdetail below, utilization of an indexed orthopedic implant 62 that isengaged by the chuck 20 may allow for maintaining the orthopedic implant62 stationary relative to the chuck 20 along the working axis 16 whileallowing forces acting on the orthopedic implant 62 to be transmitted inthe direction along the working axis 16 such that the force sensor 50may accurately measure the force imparted onto the orthopedic implant 62as it is advanced relative to the bone of the patient.

Returning to the description of the displacement sensor 42, the depthsensing arm 44 may be used to establish a reference point from whichdisplacement of an orthopedic implant 62 may be measured. In thisregard, as follows herein, a general description of the features andoperation of the instrument 10 used in conjunction with the orthopedicimplant assembly 60 is provided.

The depth sensing arm 44 may extend from the drill housing 12. Forexample, the depth sensing arm 44 may extend distally (e.g., from adistal face 14 of the drill housing 12) in a direction correspondingwith the direction in which the orthopedic implant 62 extends from thechuck 20 of the instrument 10 for advancement into a bone. At least aportion of the displacement sensing arm 44 may extend from the drillhousing 12 parallel to the working axis 16 of the instrument 10. Thedepth sensing arm 44 may also include a distal portion 46 that isadapted to engage the bushing 64 provided with the orthopedic implantassembly 60. Alternatively, the distal portion 46 may include anintegrally provided bushing 64 as described above. As used herein,distal may correspond to a direction toward the leading edge 10 a of theorthopedic implant 62 and proximal may correspond to a direction awayfrom the leading edge 10 a of the orthopedic implant 62 toward anopposite end of the orthopedic implant 62. In this regard, at least aportion of the depth sensing arm 44 (e.g., the distal portion 46) may beadapted to engage the bushing 64 of the orthopedic implant assembly 60.In any regard, at least a portion of the depth sensing arm 44 may extendinto the housing 12.

In an embodiment, the displacement sensor 40 may comprise a linearvariable differential transformer (LVDT) sensor that is adapted to sensethe position of a core 54 relative to a coil 48. Accordingly, thehousing 12 may contain a coil 48. A proximal end 52 of the displacementsensing arm 44 may include the core 54 that may interact with the coil48 of the displacement sensor 40. Specifically, as shown in FIG. 1, thedepth sensing arm 44 is in a retracted position relative to theorthopedic implant 62. For example, this retracted position shown inFIG. 1 may occur when the orthopedic implant 62 is advanced duringplacement of the orthopedic implant 62 in the bone of a patient (e.g.,such that the portion of the orthopedic implant 62 extending beyond thedistal edge of the bushing 64 would be disposed in the bone of thepatient). In this regard, the proximal end 52 of the displacementsensing arm 44 may be disposed within the coil 48 of the displacementsensor 40. Accordingly, as the proximal end 52 of the displacementsensing arm 44 is moved relative to the coil 48, the location of thecore 54 may be determined relative to the coil 48 (e.g., by monitoringthe induced current of the coil 48) to provide an output that isindicative of the position of the core 54, and in turn the position ofthe displacement sensing arm 44 relative to the drill housing 12. Thatis, the depth sensing arm 44 may be displaceable relative to the coil 48such that the displacement sensor 42 may be operable to sense a changein position of the depth sensing arm 44 and output a measure of thedisplacement that may be used in determining a depth of penetration ofthe orthopedic implant 62 relative to a bone in which the implant 62 isinserted. In an embodiment, the total measurable travel of the core 54relative to the coil 48 may be at least about 2.5 in (6.4 cm).Furthermore, the resolution of the output of the displacement sensor 42may be about 0.1% (e.g., about 0.002 inches (0.06 mm) for a sensorhaving a total measureable travel of 2.5 inches (6.4 cm)).

While a LVDT displacement sensor is shown and described in relation tothe instrument 10 shown in the accompanying figures, it may beappreciated that other types of displacement sensors may be provided.For instance, the sensor may provide for the absolute or relativemeasurement of the position of the distal end 46 of the displacementsensing arm 44 to provide a displacement measure. For instance, inanother embodiment, an optical displacement sensor may be provided.Other types of displacement sensors are also contemplated such as, forexample, a capacitive displacement sensor, ultrasonic sensors, Halleffect sensors, or any other sensors known in the art capable ofoutputting an absolute or relative position measure. In any regard, theuse of the bushing 64 that is engaged with the displacement sensing arm44 may allow for a reference point to be established using the bushing64 resting external to the substrate into which the orthopedic implant62 is advanced. For instance, a controller (described in greater detailbelow) may receive an input to reset or “zero” the measure of thedisplacement sensor 42 when the bushing and leading edge 10 a of theimplant 62 are in contact with an exterior surface of the bone intowhich the implant 62 is to be advanced. Accordingly, any relativemovement of the orthopedic implant 62 relative to the bushing 64 may bemeasured to determine the depth of penetration of the leading edge 10 aof the orthopedic implant 62 as it is advanced into a substrate (e.g., apatient's bone).

A biasing member 58 (e.g., a coil spring) may be provided relative tothe proximal end 52 of the displacement sensing arm 44. In this regard,the biasing member 58 may act on the proximal end 52 of the displacementsensing arm 44 to bias the displacement sensing arm 44 distally. Thismay assist in maintaining the bushing 64 in contact with the bone toincrease the accuracy of the displacement sensor 42.

In an embodiment, the displacement sensing arm 44 may include featuresthat selectively prevent ejection of the displacement sensing arm 44from the instrument in the distal direction when the displacementsensing arm 44 is distally biased. For example, the displacement sensingarm 44 may include at least one flat portion 66 that extends along aportion of the displacement sensing arm 44. At the proximal and distalextents of the flat 66, the displacement sensing arm 44 may includeshoulders 68 that project from the flat 66. As such, a selectivelydisplaceable stop 70 (best seen in FIGS. 2 and 3) may be disposedrelative to the flat portion 66 such that the flat portion 66 may movedistally and proximally relative to the stop 70. However, the stop 70may interfere with the shoulder 68 defined in the displacement sensingarm 44 to prevent passage of the shoulders 68 beyond the stop 70. Thatis, a distal shoulder 68 may limit proximal movement of the displacementsensing arm 44 beyond the stop and a proximal shoulder 68 may limitdistal movement of the displacement sensing arm 44 beyond the stop 70.In this regard, the length of the displacement sensing arm 44 alongwhich the flat portion 66 extends may be moveable relative to the stop70 between the distal and proximal shoulders 68 defined at the ends ofthe flat portion 66.

However, the stop 70 may be displaceable by, for example, depressing abutton 72 provided on an exterior of the housing 12. Thus, upondepressing the button 72, the stop 70 may be displaced away from thedisplacement sensing arm 44 to allow the shoulder 68 to pass by the stop70 such that the displacement sensing arm 44 may be removed from theinstrument 10. Additionally, the distal end of the flat 66 may include adetent 74 that may be engageable with the stop 70 so as to maintain thedisplacement sensing arm 44 in a proximally disposed, retracted positionrelative to the housing 12 such as that shown in FIG. 1. Once the button70 is depressed and released, the detent 74 at the proximal end of theflat portion 66 may be released by the stop 70 and the displacementsensing arm 44 may move proximally (e.g., under influence of the biasingmember 58). The displacement sensing arm 44 may move proximally untilthe shoulder 68 at the distal end of the flat 66 are engaged to preventfurther distal movement of the displacement sensing arm 44. Accordingly,the displacement sensing arm 44 may be retained in a retracted position(e.g., for improved visibility of the distal end of the orthopedicimplant 62 or to stow the displacement sensing arm 44 when not in use).However, the displacement sensing arm 44 may be released to be moveablerelative to the housing 12. Moreover, the displacement sensing arm 44may be removable altogether from the housing 12.

In the latter regard, removal of the displacement sensing arm 44 andbiasing member 58 from the instrument 10 may allow for separate cleaning(e.g., in an autoclave) of those members. Additionally, removal of thedisplacement sensing arm 44 may allow for a cleaning apparatus (e.g., abrush or the like) to be passed through the instrument 10 to facilitatecleaning thereof.

As referenced above, in an embodiment the distal portion 46 of thedisplacement sensing arm 44 may be adapted to engage the orthopedicimplant assembly 60 (e.g., a bushing 64 thereof) that is correspondinglyadapted for use with the instrument 10. In this regard, the orthopedicimplant assembly 60 may include the implant 62 and the bushing 64. Thebushing 64 may be adapted for movement along the implant 62 relative tothe working axis of the implant 62. The displacement sensing arm 44 mayengage the bushing 64 such that movement of the bushing 64 relative tothe implant 62 may also cause relative movement of the displacementsensing arm 44 relative to the implant 62. The displacement sensing arm44 may generally be linear along a proximal portion 52 of thedisplacement sensing arm 44. In this regard, the proximal portion 52 maybe adapted to be parallel with the cannulated passage 76 that extendsalong the working axis 16.

Furthermore, the distal portion 46 of the displacement sensing arm 44(e.g., the portion distal to the linear portion of the displacementsensing arm 44) may extend from the linear portion of the displacementsensing arm 44 toward the orthopedic implant assembly 60 that may beengaged by the chuck 20 of the instrument 10. In this regard, the linearportion of the displacement sensing arm 44 may be substantially parallelto and offset from the working axis 16. The distal portion 46 may extendfrom the linear portion in a direction corresponding with the offsetsuch that the distal portion 46 extends toward the orthopedic implantassembly 60. This may facilitate engagement between the displacementsensing arm 44 and the bushing 64 of the orthopedic implant assembly 60(e.g., using a post and hole as described in U.S. Pat. No. 9,370,372,which is incorporated by reference herein in its entirety).

The distal portion 46 may be an at least partially arcuate memberextending along a radius of curvature toward the orthopedic implantassembly 60. However, the distal portion 46 may be shaped differently(e.g., the distal portion 46 may be a linear portion extending at anangle or perpendicularly from the proximal portion 52 toward theorthopedic implant assembly 60). The configuration and operation of themeasurement system 40 of the instrument 10 may be as described in any ofthe embodiments in U.S. Pat. Nos. 6,665,948, 9,370,372, or U.S. PatentPub. No. 2016/0128704, all of which are incorporate by reference hereinin their entireties. Moreover, operation of the bushing 64 in relationto the displacement sensing arm 44 may be according to any of theforegoing documents incorporated by reference. In this regard, thebushing 64 may interact with the orthopedic implant 62 in a mannersimilar to that described in relation to the bushing interacting withthe drill bit or other instrument working portion described in theforegoing documents incorporate by reference.

As described briefly above, the chuck 20 may be selectively engageableand disengageable with the instrument 10. In this regard, variousdifferent chucks may be selectively utilized in conjunction with theinstrument 10. To facilitate the different chucks, the instrument 10 mayprovide a standardized chuck engagement format to engage the variousdifferent potential embodiments of chucks 20 that may be utilized withthe instrument 10. In this regard, as may be appreciated in FIG. 4, theinstrument 10 may include a corresponding chuck drive coupling 78 thatengages with a chuck 20 to impart rotational motion from the drivesystem 30 to the chuck 20. In this regard, the chuck 20 may bedetachable from the drill 50. The chuck drive coupling 78 may be inoperative communication with the drive system 30 such that the drivesystem 30 rotates the drive coupling 78. In turn, the chuck drivecoupling 78 may engage with the chuck 20 to rotate at least a portionthereof. Furthermore, any chuck 20 configured for engagement with theinstrument 10 may include a cannulated passage 22 that is alignable withthe cannulated passage 76 of the instrument when the chuck 20 is engagedtherewith.

With further reference to FIG. 5, the proximal end of the chuck 20 mayinclude a chuck drive shaft 24 disposed relative to slots 26. The slots26 may coordinate with corresponding tabs 80 provided with theinstrument 10 adjacent to the chuck drive coupling 78 (best seen in FIG.6B) to retain the chuck 20 relative to the instrument 10. In turn, thechuck drive shaft 24 may be keyed or otherwise configured such that thechuck shaft 24 engages the chuck drive coupling 78 of the instrument 10.In turn, the chuck drive coupling 78 may impart rotational motion to thechuck drive shaft 24 to rotate an orthopedic implant 62 engaged with thechuck 20. The slots 26 may coordinate with the tabs 80 so as to allowthe chuck 20 to be quickly attached and/or released from the instrument10 by engagement of the slots 26 with the tabs 80. This may beappreciated from FIG. 5, where it is illustrated that the slots 26 mayinclude a first portion 26 a that extends parallel to the working axis16.

The chuck may be advanced toward the chuck drive coupling 78 along theworking axis 16 such that the tabs 80 travel along the first portion 26a to the distal end thereof. The slots 26 may also include a secondportion 26 b that extend circumferentially about the chuck 20. As such,once the tabs 80 abut the distal end of the first portion 26 a, rotationof the chuck 20 may move the second portion 26 b such that the tabs 80extend into the second portion 26 b, thus restricting the chuck 20 frommovement relative to the working axis 16. That is, when the tabs 80 aredisposed in the second portion 26 b, the second portion 26 b may besized as to engage the tabs 80 to limit axial movement of the chuck 20relative to the working axis 16 (e.g., to allow the chuck 20 to travelrelative to the force sensor 50 for transferring force thereto, but todisallow the chuck 20 from moving distally from the instrument 10).Further locking mechanisms may be provided to prevent the chuck 20 fromrotating relative to the working axis 16 when engaged so that the tabs80 do not slip from the second portion 26 b. For example, a release maybe provided to lockingly maintain the chuck 20 in position to theinstrument 10 such that the chuck 20 is only released for removal uponactuation of the release. Thus, the chuck 20 may be quickly andefficiently attached and detached from the instrument 10.

With further reference to FIGS. 6A and 6B, cross sectional views of theinstrument 10 with orthopedic implant assembly 60 engaged therewith areshown. As may be appreciated, the chuck shaft 24 may engage the chuckdrive coupling 78. As may also be appreciated, the chuck 20 may beoperatively engaged with the instrument 10 such that the slots 26 of thechuck 20 are engaged with the tabs 80 to maintain the chuck 20 inengagement with the drive system 30. As will be appreciated in thefollowing discussion, any or all of the chuck embodiments describedbelow may have a similar engagement structure for selective engagementwith the instrument 10. In this regard, any of the following embodimentsof chucks may be interchangeably engaged with the instrument 10 forutilization with the instrument in a manner described below.

For instance, FIG. 7 depicts an embodiment of a chuck 200. The chuck 200may be utilized to engage a smooth-walled orthopedic implant such as aK-wire, IM pin, or other orthopedic implant to be placed utilizing theinstrument 10. The chuck 200 generally includes a chuck body 202 thatmay include a proximal portion having engagement features such as slots26 described above for attachment to the instrument 10. The chuck 200may include an actuation lever 204 extending from the chuck body 202.During operation, a user may grasp the actuation lever 204 to engage theorthopedic implant with the chuck 200. In this regard, the actuationlever 204 may be contoured so as to dispose a free end of the actuationlever 204 adjacent to a handle of the instrument 10 such that the usermay easily grasp the actuation lever 204 when holding the instrument 10.However, a user may be required to maintain a force or the activationlever 204 to engage an orthopedic implant 62 with the chuck 200.

With further reference to FIGS. 8 and 9, the internal components of thechuck 200 are depicted. As such, in FIG. 8, the chuck body 202 is notshown for clarity. FIG. 9 is a cross sectional view of the chuck 200taken along a plane in which the working axis 16 lies. The actuationlever 204 may be engaged with the chuck body 202 at a pivot 206. Inturn, upon movement of the actuation lever 204 by the user (e.g., bysqueezing of the actuation layer 204 by the user of the instrument 10),the actuation lever 204 may move about the pivot 206. A fork 208 may bedisposed opposite the pivot 206 from the lever arm 204. The fork 208 mayengage a collar 210 disposed within the chuck body. The collar 210 maycomprise or be in contact with a cam member 212. The cam member 212 andcollar 210 may be biased toward the proximal portion 215 of the chuckbody 202 (i.e., toward the engagement portion of the chuck 200 thatinterfaces with the instrument 10). The cam member 212 may define camsurfaces 216 that engage locking rollers 214 that may be disposed aboutthe working axis 16. The locking rollers 214 may comprise jaw membersthat engage the orthopedic implant. The cam surfaces 216 may beconfigured such that when the cam member 212 is biased proximally (e.g.,when the user is not grasping the actuation lever 204), the cam surfaces216 allow the locking rollers 214 to be displaced away from the workingaxis 16. In turn, an orthopedic implant 62 may be freely passed into thecannulated passage 218 of the chuck 200. The locking rollers 214 may bedisplaced away from the cannulated passage 218 to accommodate movementof the orthopedic implant in the cannulated passage 218 in a directionalong the working axis 16.

Upon placement of the orthopedic implant 62 at the desired locationwithin the cannulated passage 218, the user may grasp the actuationlever 204. This may cause the fork 208 to advance distally toward thedistal end 216 of the chuck 200 as the actuation lever 204 is movedproximally toward the handle of the instrument 10. The distal movementof the fork 208 may overcome the bias force applied to the collar 210and cam member 212, thus moving the cam member 212 distally. The distalmovement of the cam member 212 may advance the cam surfaces 216 relativeto the locking rollers 214. The cam surfaces 216 may be contoured suchthat upon distal advancement of the cam member 212, the locking rollers214 are urged radially toward the working axis 16. As the lockingrollers 214 may be advanced toward the working axis 16, an orthopedicimplant disposed in the cannulated passage 218 may be gripped by thelocking rollers 214 that are urged toward the working axis 16. In turn,grasping of the actuation lever 204 by the user may result in thelocking rollers 214 being urged by the cam surfaces 216 of the cammember 212, thus forcing the locking rollers 214 radially toward theorthopedic implant contained within the cannulated passage 218 preventaxial movement of the orthopedic implant within the cannulated passage218.

The chuck 200 may also include a chuck drive shaft 24 engageable withthe chuck drive coupling 78 to be rotated by the drive system 30. Inturn, radial bearings 222 may be provided to support the rotationalmovement of the chuck drive shaft 24 and/or limit axial movementthereof. The chuck drive shaft 24 may be engaged with the cam member 212such that rotational movement of the chuck drive shaft 24 also rotatesthe cam member 212. As such, when the cam member 212 is engaged with anorthopedic implant via the locking rollers 214, the orthopedic implantmay also be rotated about the working axis 16.

With further reference to FIGS. 10 and 11, another embodiment of a chuck300 is depicted. The chuck 300 may include an arrangement including acollar 210, cam member 212, and locking rollers 214 similar to thatdescribed above in relation to the embodiment 200. However, positioningof the collar 210 and cam member 212 to engage and disengage the lockingrollers 214 may be controlled by a rack and pinion mechanism 310. Therack and pinion mechanism 310 may include an actuation lever 304. Theactuation lever 304 may be within reach of the user of the instrument 10when the chuck 300 is engaged therewith. For example, the actuationlever 304 may be reached by a thumb of the user to apply force to theactuation lever 304 when the user utilizes the instrument 10. In thisregard, the actuation lever 304 may be placed on either side of thechuck 300 for ambidextrous use by a surgeon.

The actuation lever 304 may be operatively engaged for co-rotation witha gear 312. As such, a force acting in the direction of the arrow 302 inFIG. 10 may cause clockwise rotation of the gear 352 as viewed in FIG.11. The gear 312 may be meshed with a pinion gear 314 that may engage arack 316 disposed on the collar 210. In turn, upon application of theforce 302, the gear 352 may be urged into clockwise motion, thus urgingthe pinon gear 314 into counterclockwise motion. This may act upon therack 316 of the collar 210 to induce movement of the collar 210 distallyto position the cam member 212 for selective engagement of the lockingrollers 214 with the orthopedic implant disposed in the cannulatedpassage 218 of the chuck 300. The rack 316 may be locked in this engagedposition by a locking member 318. As may be appreciated, upon release ofthe force 302 (and/or release by the locking member 318), the actuationlever 304, gear 312, and pinion gear 314 may be relaxed or allowed topivot such that the biasing of the cam member 312 and collar 310disengages the locking wheels 214 from the orthopedic implant. Thelocking member 318 may engage when the actuation lever 304 is moved intoa position to engage the orthopedic implant 62. In this regard, thelocking member 318 may include a locking clutch that prevents rotationof the gear 312 in a direction corresponding to release of theorthopedic implant 62. The locking clutch may be released by movement ofthe lever actuator 304 in a direction along an axis about which the gear312 rotates. For instance, the lever actuator 304 may be moved in adirection toward or away from the gear 312 to release the locking clutchto allow the lever actuator 304 to be moved in a direction correspondingto release of the orthopedic implant 62. In other embodiments, thelocking member 318 may comprise a pin to fix the gear 312 and/or a fixedgear that is introducible in meshed engagement with the gear 312 toprevent movement thereof.

FIGS. 12 and 13 depicted another embodiment of a chuck 400. The chuck400 may include structure similar to that described in relation to thechuck 300 with the exception that the actuation lever 304 may bereplaced with a wheel 402 that may be rotatable for rotation of a gear404. The gear 404 may be directly engaged with a rack 404 disposed onthe collar 210. In turn, movement of the collar 210 to urge the cammember 212 may result from rotation of the wheel 402.

Also, the embodiment of the chuck 400 may include cam blocks 414 ratherthan locking wheels 212. The cam blocks 414 may still interact with thecam surfaces 216 of the cam member 212 such that the cam blocks 414engage and disengage an orthopedic implant with distal and proximalmovement of the cam member 212, respectively. In this regard, the camblocks 414 may comprise jaw members of the chuck 400.

FIGS. 14A, 14B, and 15 depict another embodiment of a chuck 500 may beutilized to engage an orthopedic implant 62 disposed within a cannulatedpassage 518 defined by the chuck 500. The chuck 500 may include aplurality of bearings 502 disposed within a chuck housing 504. Thebearings 502 may support a chuck driveshaft 506. The chuck driveshaft506 may be adapted for engagement with the chuck engagement coupling 78of the instrument 10. That is, the instrument may impart rotationalmovement of the chuck driveshaft 506. Chuck driveshaft 506 may include athreaded surface 508. The threaded surface 508 may be threadablyengageable with a threaded portion 510 of a cam member 512. In thisregard, the cam member 512 may be threadably engaged with the threadedsurface 508 of the chuck driveshaft 506. As such, relative rotationalmotion between the cam member 512 and the chuck driveshaft 506 may causerelative axial movement between the cam member 512 and the chuckdriveshaft 506 as the threads engage and disengage with motion. The cammember 512 may include cam surfaces 514. The cam surfaces 514 maycontact chuck blocks 516. In this regard, the cam blocks 516 may bemaintained against the cam surfaces 514 of the cam member 512 such thatthe cam blocks 516 are urged radially toward the working axis 16 upondistal movement of the cam member 512 as described above. The chuckblocks 516 may comprise jaw members of the chuck 500.

The cam member 512 may be aligned with an annular support 520 that maybe disposed within the cam body 504. The annular support 520 may includea rod 522 that may extend externally to the cam body 504. The rod 522may be supported by the annular support 520 and be biased in a directionradially away from the working axis 16. The cam member 512 may comprisea slot 524 that may be alignable with the rod 522 supported by theannular support 520. As such, when the slot 524 and the rod 522 arealigned, the rod 522 may be displaced from the externally extendingportion of rod 522 extending outside the cam body 504 such that the rod522 may be advanced radially toward the working axis 16 beyond theannular support 520 and into the slot 524. The slot 524 may bedimensioned to allow for axial movement of the cam member 512 when therod 522 is disposed in the slot 524, but the rod 522 may engage the cammember 512 to prevent rotation of the cam member 512 about the workingaxis 16. That is, advancement of the rod 522 into the slot 524 of thecam member 512 may cause the cam member 512 to be locked relative toradial rotation about the working axis 16. In turn, continued operationof the instrument 10 to induce rotation of the cam driveshaft 504 mayresult in relative rotation between the driven cam driveshaft 506, whichrotates, and the locked cam member 512, which is prevented from rotationby the rod 522. In turn, the relative rotational movement between theinternally threaded surface 508 and the threaded portion of the cammember 512 may induce relative axial movement between the cam member 512and the chuck driveshaft 506. This relative axial movement may cause thecam member 512 to be moved distally to engage the cam blocks 516 suchthat the cam blocks 516 are urged by the cam surfaces 514 of the cammember 512 to move the cam blocks 516 radially toward the axis 16 toengage the orthopedic implant 62.

In turn, the rotational motion imparted by the instrument 10 may beutilized to engage and disengage the orthopedic implant 62 of the chuck500 when the rod 522 is depressed into the slot 524. That is, uponnormal operation where the rod 522 may be biased radially away from theaxis 16 such that the slot 524 of the cam member 512 is not engaged bythe rod 522, the cam member 512 may co-rotate with chuck driveshaft 506for normal operation. As the cam member 512 may engage an orthopedicimplant 62, the orthopedic implant may also be rotated when engaged bythe cam member 512. Upon engagement of the rod 522 with the slot 524such that the rod 524 prevents radial movement of the cam member 512,continued operation of the instrument 10 may result in relativerotational motion of the chuck driveshaft 506 and the cam member 512. Assuch, the instrument 10, upon engagement of the rod 522 with the slot524 of the cam member 512, may be utilized to advance and retract thechuck blocks 516 to engage and disengage the orthopedic implant 62.

With further reference to FIGS. 50-56 another embodiment of a chuck 550is depicted. Like a number of the chucks described above, the chuck 550may allow for engagement of an orthopedic implant 62 (not shown in FIGS.50-56) without requiring external force be applied by a user of theinstrument. In this regard, the chuck 550 may be utilized in conjunctionwith an instrument 10 having a measurement system 40 as described.Because the chuck 550 may not require application of an external forceto the chuck 550 to maintain engaged with the orthopedic implant, thechuck 550 may provide more precise and accurate measurements resultingfrom the measurement system 40. Moreover, as may be appreciated from thediscussion to follow, the chuck 550 may allow for engagement of anorthopedic implant when the chuck 550 is moved in a direction to advancethe orthopedic implant 62 relative to the bone of the patient. However,the chuck 550 may, in at least some states, allow for retraction of thechuck 550 relative to the orthopedic implant such that the chuck 550disengages automatically upon retraction of the chuck 550 from theorthopedic implant. In this regard, the chuck 550 may be utilized suchthat the chuck 550 engages the orthopedic implant 62 upon a motiontending to advance the orthopedic implant 62 linearly relative to thebone of the patient. Additionally, the chuck 550 may be readilyretracted relative to the orthopedic implant such that repeatedadvancement in retraction may be accomplished without requiring the userto take additional action to engage and disengage the chuck 550 with theorthopedic implant other than merely advancing and retracting the chuck550 relative to the orthopedic implant.

With specific reference to FIG. 50, the chuck 550 may include acannulated passage 552 that generally extends along a working axis 16 ofthe chuck 550. Specifically, the cannulated passage 552 may be alignedwith the cannulated passage 76 of the instrument 10 to accept anorthopedic implant 62 relative to the cannulated passage 76 and thecannulated passage 552. In this regard, the chuck 550 may include anengagement portion 592 at a proximal end thereof that may engage theinstrument 10 in the manner described in relation to FIGS. 5-6B above.In this regard, the chuck 550 may be used interchangeably with theinstrument 10 as described above.

FIG. 51 depicts a cross-sectional view of the chuck 550 taken along theworking axis 16. The chuck 550 may include an orthopedic implantengagement portion 554. With additional reference to FIGS. 52 and 53,the orthopedic implant engagement portion 554 is shown in isolation. Theorthopedic implant engagement portion 554 may include a drive shaft 562that may engage a chuck drive coupling 78 as described above. In thisregard, the instrument 10 may be operative to impart rotational motionto the orthopedic implant engagement portion 554 when the engagementportion 592 is engaged with the instrument 10.

The orthopedic implant engagement portion 554 may also include aplurality of roller members 556. The roller members 556 may be disposedradially about the cannulated passage 552. The roller members 556 maycomprise a plurality of jaw members that are used to engage anorthopedic implant disposed in the cannulated passage 552. While threeroller members 556 are shown, additional or fewer roller members may beprovided. As shown, the roller members 556 may be disposed about theworking axis 16 such that the rollers 556 are disposed at various radialpositions about the cannulated passage 556. The roller members 556 maybe evenly spaced about the cannulated passage 556. While not shown, theroller members 556 may be provided in opposing pairs such that eachroller member 556 may have a coordinating roller member 556 spacedopposite the cannulated passage 556. This arrangement may assist inimparting a clamping force to an orthopedic implant as described ingreater detail below.

The roller members 556 may be engaged with the orthopedic implantengagement portion 554 such that the roller members 556 are pivotalabout an axle member 558. The axle member 558 may define a pivot axis560. Specifically, the pivot axis 560 may be orthogonal to the workingaxis 16 and offset there from. In turn, the roller members 556 may beoperative to pivot toward or away from the working axis 16 upon pivotalmovement about the axle 558. With specific reference to FIG. 53, it maybe appreciated that upon clockwise rotation of the roller member 556shown in cross-section in FIG. 53, the roller member 556 may pivottoward the working axis 16. In turn, clockwise rotation of the rollermember 556 may result in the roller member 556 engaging an orthopedicimplant disposed within the cannulated passage 552.

With further reference to FIG. 54, the orthopedic implant engagementportion 554 is shown in relative position with a cam member 564, whichis also depicted in FIG. 51. Specifically, the cam member 564 mayinclude an annular ramp surface 568 that may be disposed so as tocontact the roller members 556 of the orthopedic implant engagementportion 554 on a side of the roller members 556 opposite the sideadjacent to the working axis 16. With returned reference to FIG. 51, thecam member 564 may be abutted distally with a bearing 570 that is inturn distally abutted by a drive ring 594. A biasing member 586 may bedeposed distally to the drive ring 594 and between the drive ring 594and an endcap 584 of the chuck 550. The biasing member 586 may serve tobias the drive ring 594, bearing 570, and cam member 564 proximally suchthat the ramped surface 568 engages with and urges the roller members556 toward the working axis 16.

Accordingly, it may be appreciated that when an orthopedic implant isdisposed in the cannulated passage 552, the roller members 556 may bebiased into contactable engagement with the orthopedic implant uponinfluence by the ramp surface 568 of the cam member 564, which is biasedproximally by the biasing member 586. Additionally, the axle 558 mayengage the roller member 556 in an eccentric manner relative to theroller member 556. In turn, the pivotal axis 560 of the roller member556 may be located proximally relative to the center of the rollermember 556. In this regard, as the chuck 550 is advanced distallyrelative to the orthopedic implant 62, the roller member 556 may contactthe orthopedic implant. The frictional engagement between the rollermember 556 and the orthopedic implant may cause the roller member toexperience a moment acting on the roller member 556 that tends to pivotthe roller member 556 about the axle 558, thus driving the roller member556 toward the working axis 16. That is, as the chuck 550 is advanceddistally relative to an orthopedic implant with which the roller member556 is in contact, the roller member 556 is further urged intoengagement with the orthopedic implant such that the orthopedic implantengagement portion 554 clampingly engages the orthopedic implant.

However, upon a motion to retract the chuck 550 relative to theorthopedic implant, the frictional engagement between the orthopedicimplant in the roller member 556 may cause the roller member to undergopivotal rotation about the axle 558 in a direction opposite of that whenthe chuck 550 is advanced. The motion to retract the chuck 550 mayresult in the roller member 556 being frictionally engaged to induce amoment on the roller member 556 that rotates the roller member 556 in adirection opposite of that when the chuck 550 is advanced such that theroller member 556 is displaced away from the working axis 16. In turn,the roller member 556 may bear against the ramp surface 558 causing thecam member 564, bearing 570, and drive ring 594 to move distally againstthe force of the biasing member 586. In turn, the roller member 556 maybe displaced away from the orthopedic implant, thus allowing the chuck550 to be withdrawn proximally relative to the orthopedic implant.However, upon further advancement of the chuck 550 distally relative tothe orthopedic implant, the roller member 556 may again be pivoted aboutthe axle 558 in a direction tending to rotate the roller member 556 in adirection towards the working axis 16 to again clampingly the orthopedicimplant disposed within the cannulated passage 552.

Thus, the operation of the chuck 550 may include a biased state whereinthe chuck 550 may clampingly engage an orthopedic implant upon a linearmotion of advancement of the chuck 550 relative to the orthopedicimplant. Such engagement of the orthopedic implant upon the motion oflinear advancement of the chuck 550 may result from the biasing forceimposed by the biasing member 586 on the cam member 564 such that theramp 568 causes the roller members 556 to contact the orthopedic implantdisposed within the cannulated passage 552 of the chuck 550. However,the chuck 550 may also be disposed in a number of alternative states,namely a locked open and a lock closed state. The various states of thechuck 550 may be controlled by operation of a control ring 572. Namely,the control ring 572 may have a set screw 588 engaged with the controlring 572 and extending radially toward the working axis 16. The setscrew 588 may extend through a side wall 596 of the chuck 550 and bedisposed within a slot 580 that is provided in the drive ring 594 asbest seen in FIGS. 55-56.

The slot 580 may include an angled portion 578 extending relative to thering member 594. When the set screw 588 is disposed in the angledportion 578 of the slot 580, the control ring 572 and set screw 588 mayallow the drive ring 594 to freely move relative to the set screw 588.That is, movement of the drive ring 594, and in turn the cam member 564,may be unrestrained for proximal and distal axial movement withconcurrent movement of the set screw 588 relative to the angled portion578 of the slot 580. In turn, upon influence of the biasing member 586and in response to the influence of the roller members 556 on the rampsurface 568, the ring member 594 may be allowed to freely move when theset screw 588 is disposed within the angled portion 578 of the angledslot 580. In addition to the slot 580, a guide slot 576 may be definedin the chuck sidewall 596. The set screw 588 may also pass through theguide slot 576 of the chuck sidewall 596. The guide slot 576 may extendcircumferentially along a portion of the circumference of the chucksidewall 596 that corresponds to the circumferential extent of the slot580. In turn, as the set screw 588 traverses along the angled portion578 of the slot 580, the set screw 588 may also move relative to theguide slot 576. In this regard, the control ring 572 may rotatecircumferentially upon movement of the drive ring 594 in a proximal ordistal axial direction.

Additionally, the angled slot 580 may include a flat portion 582 thatextends circumferentially. When the control ring 572 is rotated so as todisposed the set screw 588 in the flat portion 580, the ring member 594may be prevented from moving axially. Specifically, the flat portion 582may be at the proximal end of the angled slot 580. In this regard, whenthe set screw 588 is disposed in the flat portion 582, the ring member594 may be disposed in a locked axial position that is a distalposition, thus locking the ring member 594 distally against theinfluence of the biasing member 586 such that the cam member 564 andramp surface 568 do not bear upon the roller members 556. Accordingly,motion of the roller member 556 in either movement of advancement orretraction relative to an orthopedic implant disposed within thecannulated portion 552 may not result in sufficient frictionalengagement between the roller member 556 and the orthopedic implant toresult in movement of the roller member 556. In turn, when the set screw588 is disposed within the flat portion 582 of the angled slot 580, thering member 594 may be locked distally such that the chuck 550 is in alocked open state and the chuck 550 does not engage the orthopedicimplant whether moved in a linear motion of advancement or retractionrelative to the orthopedic implant.

Additionally, the chuck 550 may be also disposed in a lock closed state.In this regard, a threaded sleeve 574 may be disposed on the controlring 572. The threaded sleeve 574 may be threadably engaged with thecontrol ring 572. In turn, the threaded sleeve 574 may be moved inthreaded engagement relative to the control ring 572 such that thethreaded sleeve 574 abuts a bulkhead 590 of the chuck 550. In turn, whenthe threaded sleeve 574 is tightened against the bulkhead 590, anyrotation of the control ring 572 may be prevented. As such, the setscrew 588 may not be allowed to traverse within the guide slot 576. Inthis regard, the set screw 588 may also prevent distal movement of thedrive member 594, bearing 570, and cam member 564. In this regard, theroller members 556 may be locked into engagement with an orthopedicimplant disposed within the cannulated passage 552. In this regard, evenupon a motion of retraction of the chuck 550 relative to the orthopedicimplant 62, the roller member 556 may not be allowed to displace the cammember 564 such that the roller member 556 remains engaged with theorthopedic implant even upon retraction.

FIGS. 57-66 illustrate a further embodiment of a chuck 950 may beutilized to engage an orthopedic implant (not shown) upon relativemotion of the chuck 950 relative to the orthopedic implant. In contrastto the embodiment of the chuck 550 described above, the chuck 950 mayhave a state in which the chuck 950 may engage the orthopedic implantupon relative rotational motion of the chuck 950 in relation to theorthopedic implant. In this regard, upon rotation in a first direction(e.g., clockwise), the chuck 950 may be operative to engage theorthopedic implant for advancement thereof. However, counter rotation(e.g., counterclockwise) of the chuck 950 relative to the orthopedicimplant may allow for the orthopedic implant to be disengaged by thechuck 950. In turn, upon the counter rotation of the chuck 950 relativeto the orthopedic implant, the chuck 950 may be retracted relative tothe orthopedic implant. Upon further rotation of the chuck 950 relativeto the orthopedic implant, the orthopedic implant may be again engagedfor further advancement thereof. In this regard, the embodiment of thechuck 950 depicted in FIGS. 57-66 may allow for selective engagement anddisengagement of the orthopedic implant of the chuck 950 withoutrequiring a user to actively interface with the chuck 950 for engagementand disengagement of the chuck 950 with the orthopedic implant. Inaddition, the chuck 950 may engage the chuck upon linear advancement ofthe chuck 950 as described above in relation to the embodiment of thechuck 550.

With initial reference to FIG. 57, the chuck 950 may include acannulated passage 952 that generally extends along a working axis 16 ofthe chuck 950. Like the cannulated passage 552 described above inrelation to chuck 550, the cannulated passage 952 may be alignable witha cannulated passage 76 of an instrument 10 to accept an orthopedicimplant 62 (not shown in FIGS. 57-66) in the cannulated passage 76 andcannulated passage 952. The chuck 950 may also include an engagementportion 952 at the proximal end thereof that may engage the instrument10 in the manner described in relation to FIGS. 5-6B above. Accordingly,the chuck 950 may also be interchangeable with the instrument 10 in amanner as described above.

FIG. 58 depicts a cross-sectional view of the chuck 950 taken along theworking axis 16. The chuck 950 may also include an orthopedic engagementportion 954 which is shown in isolation and FIGS. 59-63. The orthopedicimplant engagement portion 954 may include a driveshaft 962 that mayengage a chuck drive coupling 78 as described above. Accordingly, theinstrument 10 may be operative to impart rotational motion to theorthopedic implant engagement portion 954 when the engagement portion992 is engaged with the instrument.

As can be appreciated in FIGS. 59-63, the orthopedic implant engagementportion 954 may include a plurality of spherical members 956 that aredisposed within helical channels 958 of the orthopedic implantengagement portion 954. Specifically, the spherical members 956 mayextend into the cannulated passage 952. Accordingly, the sphericalmembers 956 may comprise jaw members for clampingly engaging anorthopedic implant disposed within the cannulated passage 952. Thehelical channels 958 may be defined in a slide member 960. As may beappreciated, the slide member 960 may move axially relative to thecannulated passage 592. When the slide member 960 is moved proximally,the spherical members 956 may be allowed to move away from the workingaxis 16. That is, the helical channels 958 may be shaped such that thedistal portions thereof allow movement of the spherical members 956 awayfrom the working axis 16. However, when the slide member 960 is moveddistally, the spherical members 956 may be moved proximally relative tothe helical channels 958, which may constrict such that the sphericalmembers 956 are urged towards the working axis 16.

A cam member 964 having a ramp surface 968 may be provided in positionrelative to the slide member 960. The cam member 964 may urge the slidemember 960 distally under influence of a biasing member 986 as best seenin FIG. 58. Moreover, the helical channels 958 may be arranged such thatrotation in a first direction may further urge the spherical members 956towards a proximal portion of the helical channels 958, thus causing thespherical members 956 to be urged towards the working axis 16. Incontrast, rotation in a second direction opposite the first directionmay tend to cause the helical channels 958 to urge the slide member 960proximally against the force imparted by the biasing member 986 suchthat the spherical members 956 may move distally relative to the helicalchannels 958, thus allowing the spherical members 956 to move away fromthe working axis 16.

Accordingly, rotation in the first direction (e.g., a direction tendingto induce advancement of an orthopedic implant) may cause the slidemember 960 to move distally such that the spherical members 956 areurged towards a proximal portion of the helical channels 958 such thatthe spherical members 956 are urged toward the working axis 16 toclampingly engage an orthopedic implant disposed within the cannulatedpassage 952 of the chuck 950. In contrast, counter rotation of the chuck950 in a direction opposite the first direction may result in thespherical members 956 acting on the helical channels 958 to cause thespherical members 956 to move distally relative to the helical channels958, thus causing proximal motion of the slide member 960 against theforce imparted by the biasing member 986 allowing the spherical members956 to move away from the working axis 16. That is, rotation of thefirst direction may cause the spherical members 956 to clampingly engagean orthopedic implant disposed in the cannulated passage 952 androtation in the second direction may cause the spherical members 956 torelease the orthopedic implant.

With returned reference to FIG. 58 and with further reference to FIGS.64-66, the chuck 950 may include features that, like the chuck 550,allow the chuck to be disposed between a biased state, a locked openstate, and a lock closed state. The chuck 950 may include a control ring972 that includes a set screw 988 engaged therewith such that the setscrew 988 extends radially towards the working axis 16. Specifically,the set screw 988 may pass through a guide slot 976 and a side wall 996of the chuck 950. The set screw 988 may also engage a slot 980 disposedin a drive ring 994. The drive ring 994 may be constrainedly engagedwith the cam member 964 for co-movement therewith. In turn, when the setscrew 988 is disposed in an angled portion 978 of the slot 980, thedrive ring 994 may be allowed to move proximally or distally based onthe movement of the cam member 964 under the influence described abovein relation to rotation of the orthopedic engagement portion 954. Thatis, when the set screw 988 is disposed in the angled portion 978 of theslot 980, the set screw 988 may be allowed to move within the guideslide 976 such that the drive ring 994 may be moved proximally indistally. The drive ring 994 may be biased to a distal position by thebiasing member 986. Thus, the chuck 950 may engage and disengage anorthopedic implant based on induced rotation of the orthopedic implantengagement portion 954 as described above.

However, the chuck 950 may also be disposed in a locked open state.Specifically, the control ring 972 may be rotated such that the setscrew 988 engages a flat portion 982 of the slot 980 that extendscircumferentially relative to the working axis 16. In this regard, whenthe set screw 988 is disposed in the flat portion 982 of the slot 980,the drive ring 994 may not be allowed to move axially. As the flatportion 982 may be disposed at a distal end of the slot 980, the drivering 994 may be locked in a proximal position against the influence ofthe biasing member 986. In this regard, the cam member 964 may also bemoved proximally relative to the slide member 960 such that thespherical members 956 are allowed to move away from the working axis 16by moving into the distal portions of the helical channels 958. In turn,when the set screw 988 is disposed in the flat portion 982 of the slot980, the chuck 950 may be in a locked open state such that the sphericalmembers 956 did not engage the orthopedic implant regardless of whetherrotated in the first direction and a second rotation.

The chuck 950 may also be disposed in a lock closed state. The controlring 972 may have a threaded lock ring 974 in threaded engagement withthe control ring 972. In this regard, when the set screw 988 is disposedin the angled portion 978 of the slot 980 and the spherical members 956are disposed in clamping engagement with the orthopedic implant in thecannulated passage 952, the lock ring 974 may be advanced distallyrelative to the control ring 972 until the lock ring 974 abuts the end984. In turn, the lock ring 974 may be tightened against the endcap 984by further distal advancement of the lock ring 974 relative to thecontrol ring 972 by threaded engagement therebetween. In turn, thecontrol ring 972 may be prevented from undergoing further rotation suchthat the set screw 988 may be disposed in a set position and the angledportion 978 such that the cam member 964 is locked in a distal position,thus causing the spherical members 956 to be maintained in a positiontowards the working axis 16 such that the orthopedic implant is engagedregardless of the direction of rotation of the chuck 950.

The foregoing embodiments of chucks may be utilized to engagetraditional orthopedic implants (e.g., smooth walled implants).Accordingly, these chuck embodiments may, in at least some applications,be utilized during traditional operations where the measurement system40 of the instrument 10 may not be utilized. As such, the components ofthe measurement system 40 (e.g., the displacement sensing on 44 andparticularly the distal portion 46 of the displacement sensing arm 44)may not be utilized. In one embodiment, the structure of thedisplacement sensing arm 44 described above allows the distal portion 46to be maintained in a stowed, proximal position relative to theorthopedic implant 62. That is, the detent 74 on the displacementsensing arm 44 may be engaged by the stop 70 such that the displacementsensing arm 44 is retained in the proximal, stowed position. This may beutilized to maintain the displacement sensing on 44 in a position thatreduces interference of the components of the measurement system 40 withtraditional implant placement operations.

FIGS. 16 and 17 depict another embodiment of a mechanism for maintainingthe displacement sensing arm 44 in a stowed position relative to theorthopedic implant engaged by the chuck 20 when the placement sensing on44 is not utilized. The embodiment described in FIGS. 16 and 17 may beutilized in place of or in addition to the structure of the displacementsensing arm 44 described above for maintaining the displacement sensingon 44 and a proximately biased position. FIGS. 16 and 17 depict anembodiment of a displacement sensing arm retention member 600. Theretention member 600 may include a clasp 604 adapted to engage thedisplacement sensing arm 44 of the instrument 10. Specifically, theclasp 604 may include a contoured pocket 606. The contoured pocket 606may be shaped to accommodate the distal portion 46 of the displacementsensing arm 44. Specifically, the contoured pocket 606 may be shaped toaccommodate the portion of the distal portion 46 of the displacementsensing arm 44 that is aligned with the clasp 604 when the displacementsensing arm 44 is arranged in a proximal, stowed position such as thatshown in FIG. 1.

The clasp 604 may be displaceable relative to the displacement sensingarm 44 so as to allow the clasp 604 to be moved to allow thedisplacement sensing arm 44 to move while displacement sensing on 44 isplaced into the proximal, stowed position shown in FIG. 1. Once thedisplacement sensing arm 44 is in place, the clasp 604 may be moved toengage the displacement sensing arm 44 such that the contoured pocket606 is provided about at least a portion of the distal portion 46 ofdisplacement sensing arm 44. The engagement of the displacement sensingarm 44 by the contoured pocket 606 may limit the distal movement of thedisplacement sensing arm 44 such that the displacement sensing arm 44 ismaintained in the proximal position.

The clasp 604 may be mounted on a ring 602 that extends about the chuck20. In this regard, the ring 602 may be rotated about the working axis16 so as to move the clasp 604 between the engaged position shown inFIG. 16 and the disengaged position shown in FIG. 17. The ring 602 mayalso include a lug 608 to help assist manipulation of the ring 602 tomove the clasp 604 between the engaged position and the disengagedposition. As such, the retention member 600 may be utilized to maintainthe displacement sensing arm 44 in the proximal, stowed position shownin FIG. 1 was to reduce interference of the displacement sensing arm 44with the orthopedic implant 62 when the instrument 10 is utilized. Whilethe retention member is shown in relation to the embodiment of the chuck200 having a lever arm 204, it may be appreciated that the retentionmember may be provided with any of the other chuck embodiments describedabove or other chuck embodiments without limitation.

There may also be times in which an orthopedic implant may be disposedin a chuck, but not engaged by locking rollers, cam blocks, or other jawstructures of a chuck. However, the surgeon may want the orthopedicimplant to remain in its place relative to a chuck absent movement ofthe orthopedic implant manually by the surgeon. For example, prior toengagement of the orthopedic implant by the jaws of the chuck, thesurgeon may place the orthopedic implant in the cannulated passage in aspecific position. The surgeon may then move the surgical instrumentwithout engaging an actuation lever or otherwise closing a jaw structureof a chuck. When the surgeon then actuates the actuation lever, it isdesirable that the orthopedic implant be in the original position thatthe orthopedic implant was placed in.

As such, FIGS. 45 and 46 depict another embodiment of a chuck 1000. Thechuck 1000 may include features that facilitate holding an orthopedicimplant 62 even when a chuck jaw member (i.e., locking roller 214) isdisengaged from the orthopedic implant 62. In this regard, a force bythe surgeon that is manually applied to the orthopedic implant 62 tomove the orthopedic implant 62 along or about the axis may befacilitated by, but absent an external force by the user, the orthopedicimplant 62 remains stationary. For instance, the force of gravity maynot cause the orthopedic implant 62 to slide in the cannulated passage218. As such, the chuck 1000 may include an implant holder 230 forretaining the orthopedic implant 62 without requiring any force by theuser. Upon placement of the orthopedic implant 62 inside the cannulatedpassage 218, the implant holder 230 may retain the orthopedic implant 62to help prevent axial or rotational movement of the orthopedic implant62 relative to the chuck 1000 during use when not engaged by theactuation lever 204 of the chuck or otherwise closing the lockingrollers 214. In one configuration, at least one gripper 234 (e.g., ballbearings, rollers, etc.) may be biased toward the center of thecannulated passage 218 by a spring 238 (e.g., a constant force spring).When the orthopedic implant 62 is inserted into the cannulated passage218 and contacts the grippers 234, the grippers 234 overcome the spring238 bias and are radially displaced away from the working axis 16. Whenthe grippers 234 are displaced, the spring 238 maintains its bias on thegrippers 234 and the grippers 234 on the orthopedic implant 62.

It can be appreciated that use of ball bearing as grippers 234 allowsfor axial translation or rotation of the orthopedic implant 62 inrelation to the chuck 1000. Ball bearings allow for the coefficient offriction to be relatively easy to overcome yet still is high enough toretain the orthopedic implant 62 in place when external forces are notapplied. The force required by the surgeon to rotate or slide theorthopedic implant 62 about or along the axis may be equal.Alternatively, rollers may be used as grippers 234. Use of rollers asgrippers 234 allows for ease of movement upon application of an externalforce by a surgeon in one direction, however, it may require more forceto move the orthopedic implant 62 in an another direction. For example,if rollers are oriented in a chuck such that the axis which the rollersrotate about is perpendicular to the axis of the cannulated passage 218,the force required to move the orthopedic implant 62 axially may be lessthan that required to rotate the orthopedic implant 62. Alternatively,if the axis of rotation of the rollers is oriented parallel to thecannulated passage 218 then the force required to move the orthopedicimplant 62 along the axis of the cannulated passage 218 may be higherthan the force required to rotate the orthopedic implant 62.

FIG. 46 depicts a cross-section of the implant holder 230 in thenormally closed position. When the orthopedic implant 62 is insertedinto the cannulated passage 218, the diameter of the orthopedic implant62 may be greater than spacing 242 created by the shape of the grippers234. If ball bearing type grippers 234 are used the diameter of the ballbearings may be adjusted to accommodate a narrower orthopedic implant62. Additionally, the implant holder 230 may retain any diameterorthopedic implant 62 up to the diameter of the cannulated passage 218.

In this regard, it can be appreciated that though the implant holder 230is only shown in FIGS. 45 & 46, it may be implemented in any of thechucks discussed herein (including those used with traditional smoothwalled implants and indexed implants discussed below). Furthermore,though the implant holder 230 shown in FIGS. 45 & 46 includes a spring238 biasing grippers 234 toward the working axis 16, any device forretaining the orthopedic implant 62 which allows motion upon applicationof external force is suitable. Further, an elastic strip or collar maybe used instead of a spring to bias the grippers 234 toward the workingaxis.

As briefly described above, use of the measurement system 40 to place anorthopedic implant may result in a number of benefits. Namely, a usermay not be required to guess or rely on “feel” alone in placement of theimplant. Rather, the measurement system may allow for selection ofvarious modes to allow for different placements of the orthopedicimplant such that the position of the implant is automaticallydetermined based on the sensors of the measurement system 40. This mayallow the implant to be placed more reliably and more efficiently. Assuch, the complexity, risk, cost, and time of operations may be reduced.

While some of the foregoing embodiments allow for engagement of anorthopedic implant without requiring application of an external force tothe chuck, other embodiments may be provided that may also assist inreducing the potential for slippage between the implant and the chuck soas to accurately measure a displacement of the instrument and/or andaccurate force measure.

In turn, an embodiment of an orthopedic implant is provided herein thatmay include a plurality of indexing features disposed along at least aportion of the length of the orthopedic implant relative to the workingaxis 16. In this regard, a corresponding chuck 20 may be provided toengage one or more of the plurality of indexing features of theorthopedic implant. In turn, the orthopedic implant may be engagedwithout an external force acting on the chuck such that the orthopedicimplant is maintained stationary along the working axis. Also, the chuckdescribed herein may provide for efficient engagement and disengagementof the orthopedic implant for efficient operation of the chuck. Forinstance, the chuck may be manipulated by a single hand of the user forengagement and disengagement of the orthopedic implant.

With further reference to FIG. 18, one embodiment of an orthopedicimplant 62 comprising a plurality of indexing features 66 is shown. Theindexing feature 66 may comprise a notch or indentation on the exteriorsurface of the orthopedic implant 62. The orthopedic implant 62 mayinclude a distal portion 62 a that is advanced into the bone of thepatient and a proximal portion 62 b disposed on a side of the orthopedicimplant 62 opposite the proximal portion 62 a. In at least someembodiments, the proximal portion 62 a and the distal portion 62 b maybe identical such that either end may comprise a feature to allow foradvancement of the implant into the bone of a patient. For instance,either or both ends may include a sharpened end, a threaded portion,flutes or other feature that assists in advancement of the proximalportion 62 a into the bone of the patient. The orthopedic implant 62 mayinclude a cylindrical body member 68 extending between the proximalportion 62 a and the distal portion 62B. In this regard, the indexingfeature 66 may include an inset engagement surface 82 that is insetrelative to the cylindrical body 68. For instance, the surface 82 mayextend along a cord length relative to the circular cross-section of thecylindrical body 68. In an embodiment shown in FIG. 18, the indexingfeatures 66 may include corresponding opposing surfaces 82 that arecoextensive relative to a length extending along the working axis 16.That is, the indexing features 66 may include offset notches withopposing engagement surfaces 82 that occupy the same length along theworking axis 16.

In contrast, FIG. 19 and FIG. 19A (which provides a detailed view of theengagement features 66 of the embodiment depicted in FIG. 19) depict analternative embodiment of an orthopedic implant 62 whereby the indexingfeatures 66 may comprise offset opposing engagement surfaces 82 that areoffset relative to a length corresponding to the working axis 16. Thatis, each given engagement surface 82 corresponding to the inset portionof the indexing feature 66 may be disposed between adjacent engagementsurfaces 82 provided on an opposite portion of the implant 62 (e.g.,opposite meaning disposed roughly 180° about the working axis 16). Inthis regard, the indexing member 66 comprise staggered offset opposingengagement surfaces 82 where adjacent opposing engagement surfaces 82are staggered along a length corresponding to the working axis 16. Withfurther reference to FIG. 20, another embodiment is shown whereby theopposing engagement surfaces 82 may be alternating such that no portionof the opposing engagement surfaces 82 overlap in a length correspondingto the working axis 16.

With further reference to FIG. 21, an embodiment of a chuck 700 isdepicted that may be used to selectively engage an orthopedic implant 62having a plurality of indexing features as described above. The use of achuck 700 that engages an indexed orthopedic implant may provide theability to utilize the measurement system 40 of the instrument 10 suchthat no external forces are required to engage the implant, yet theimplant is securely engaged and easily engaged/disengaged.

Specifically, the instrument 10 may include a force sensor 50 capable ofoutputting a signal indicative of the force acting axially on theleading edge 10 a of the orthopedic implant 62 as it is advanced throughthe bone of the patient. The force sensor 50 may be disposed proximallyrelative to the drive system 30. In this regard, the drive system 30,chuck 20, and engaged implant 62 may be axially rigid such that a forceacting on the leading edge 10 a of the orthopedic implant 62 may causethe force to be transmitted through the implant 62, chuck 20, and drivesystem 30 to act on the force sensor 50. As addressed above, relying onexternal forces to engage the implant 62 may result in inaccuracies ofthe measurement system 40.

However, the coordination of the chuck 700 with an orthopedic implantsuch as those described above having a plurality of index features 66may allow for the orthopedic implant 62 to be axially fixed relative tothe chuck 20 allow for free transmission of force from the orthopedicimplant 62 to the chuck 20 and to the drive system 30 for accuratemeasurement at the force sensor 50 without inducement of additional ordifferent forces resulting from the engagement of the orthopedic implant62 by the chuck 20.

With further reference to the chuck 700 depicted in FIG. 21-30, thechuck 700 may include a chuck body 702. The chuck body 702 may comprisean engagement portion 704 at the proximal end of the chuck 700 that, asdescribed above, may be used to interface with the instrument 10. Thechuck 700 may also include an engagement control member 706. Acannulated passage 708 may be provided into which an orthopedic implant62 may be provided as shown in various ones of FIGS. 21-30. As wediscussed in greater detail below, the engagement control number 706 maycorrespond to a control ring that is rotatable relative to the chuckbody 702 to control engagement and disengagement of the orthopedicimplant 62. In this regard, the chuck 700 may also include a button 710may be depressed to allow for immobilization of a chuck drive shaft toallow for relative movement between the engagement control number 706and a chuck drive shaft described in greater detail below.

The chuck 700 may include a distal plate 712. The distal place 712 maybe secured to a chuck drive shaft 722. For instance, the distal plate712 may be bolted to the chuck drive shaft 722 by pivot members 714 and716. For instance, the pivot members 714 and 716 may comprise threadedportions engaged with the chuck drive shaft 722. With further referenceto FIG. 22 where the distal plate 712 has been removed for illustrationpurposes, the pivot members 714 and 716 may include bearing surfaces(i.e., non threaded portions) that may support a first jaw member 718and a second jaw member 720, respectively. The first jaw member 718 maybe disposed for relative movement about a first axis defined by pivotmember 714. The second jaw member 720 may be disposed for relativemovement about a second axis defined by the pivot member 716. As may beappreciated in FIG. 23, the first jaw member 718 and second jaw member720 may be disposed relative to the cannulated passage 708 such that thejaw members 718 and 720 may be moved radially toward and away from theworking axis 16 to engage the orthopedic implant 62.

The chuck driveshaft 722 may engage with the chuck drive coupling 78 ofthe instrument 10. In this regard, upon operation of the drive system30, the chuck driveshaft 722 may be rotated. As described above, thepivot member 714 and 716 may be engaged with the chuck driveshaft 722.As such, upon rotation of the chuck drive shaft 722, the pivot members714 and 716 may also be rotated as are the first jaw member 718 andsecond jaw member 720 supported by the pivot members 714 and 716,respectively. In turn, when the jaw members 718 and 720 are engaged withan orthopedic implant 62, rotational motion is also imparted to theorthopedic implant 62.

The button 710 may include a displaceable rod 724. A correspondingpocket 726 may be provided on the chuck driveshaft 722. In this regard,the pocket 726 may be aligned with the button 710 such that when thebutton 710 is displaced, the rod 724 may extend into the pocket 726.This may rotationally lock the chuck driveshaft 722 relative to thechuck body 702. In turn, the engagement control member 706 may berotated relative to the chuck drive shaft 722. The engagement controlmember 706 may be biased by a biasing member 728. The biasing member 728may bias the engagement control member 706 into a position that alsobiases the first jaw member 718 and the second jaw member 720 toward theworking axis 16.

With further reference to FIGS. 28, 29, and 30, the engagement controlmember 706 is shown relative to the first jaw member 718 and the secondjaw member 720 at two locations along the working axis 16. The first jawmember 718 may include a first follower portion 734 disposed relative toa first cam surface 730 of the engagement control member 706. That is,the engagement control member 706 may define a first cam surface 730with which the first follower portion 734 is engaged. The second jawmember 720 may include a second follower portion 736 arranged relativeto a second cam surface 732 defined by the engagement control member706. Accordingly, upon rotation of the engagement control member 706,(e.g., against the biasing force induced by the biasing member 728), thefirst cam surface 730 and the second cam surface 732 may be movedrelative to the first and second jaw members 718 and 720 such that thefirst follower portion 732 and the second follower portion 734 areengaged by the respective cam surface 734 or 746. Upon rotation of theengagement control member 706, the first follower portion 734 and thesecond follower portion 736 may be engaged so as to induce rotation ofthe first jaw member 718 about the first pivot member 714 and the secondjaw member 716 about the second pivot member 716. As the respectivefollower portion 734 or 736 is disposed opposite the corresponding pivotmember 714 or 716, rotation of the engagement control member 706 may acton each respective jaw member 718 or 720 to lever the jaw member 718 or720 away from the working axis 16. This pivotal motion of the jawmembers 718 and 720 relative to the pivot members 714 and 716 may resultin the jaw members being radially moved away from the working axis 16.

For instance, FIG. 24 depicts a condition where the engagement controlmember 706 has been rotated relative to the chuck drive shaft 722 suchthat the cam surfaces 730 and 732 engage the follower portions 734 and736 to move the jaw members 718 and 720 radially away from the work axis16. In this regard, the orthopedic implant 62 may be inserted in thecannulated passage 708 as shown in FIG. 25. With further reference toFIGS. 26 and 27, the engagement control member 706 may be released. Inturn, the bias member 728 may return the engagement control member 706to a resting position such that the jaw members 718 and 720 are urged bythe cam surfaces 730 and 732 acting on the follower portions 734 and 736to cause the jaw members 718 and 720 to move radially inward toward andbe biased toward the axis 16 under action of the biasing member 728 toengage an orthopedic implant in the cannulated passage 708.

One or more the plurality of index features 66 provided on theorthopedic implant 62 may be engaged by one or more of the jaw members718 and 720. Specifically, the first and second jaw members 718 and 720may include teeth members 738 correspondingly sized to engage the indexfeature 66 of an orthopedic implant 62. That is, the teeth members 738may bear against the engagement surface 82 defined by the index feature66 to engage the orthopedic implant 62. As the teeth members 738 mayengage the engagement surface 82 of the orthopedic implant that isoffset inward toward the working axis 16, the engagement feature 66 maydefine a shoulder that is engaged by the teeth members 738. As such, theinteraction of the teeth member 738 with the orthopedic implant 62 mayprevent relative axial movement between the orthopedic implant 62 andthe chuck 700. However, force acting on the orthopedic implant 62 in adirection along the working axis 16 may still be imparted on the chuck700 which may act upon the drive system 30 to bear against the forsensor 50 such that the force acting on the orthopedic implant 62 may beaccurately measured.

As described above, a variety of different arrangements of indexingfeature configurations may be provided on various embodiments of theorthopedic implant 62. In this regard, the jaw members 718 and 720, andspecifically the teeth portions 738 may be sized correspondingly engagewith the index features of a given orthopedic implant 62 to be used. Assuch, the jaw members 718 and 720 maybe offset relative to the workingaxis 16 such that a plurality of offset index features 66 at differentpositions along the working axis 16 of the orthopedic implant 62 (e.g.,such as those shown in FIGS. 19, 19A, and 20) may be engaged by theteeth members 738. This may provide positive engagement to reduce thepotential that the orthopedic implant 62 moves actually relative to thechuck 700 or slips rotationally relative to the chuck 700 duringoperation. However, other arrangements may be provided such ascorresponding teeth portion 738 to engage an orthopedic implant as shownin FIG. 18 where the plurality of index member 66 are provided oncoextensive portions of the length of the orthopedic implant 62 alongthe working axis 16 such the teeth 738 do not overlap.

With additional reference to FIGS. 31-35, another embodiment of a chuck750 is shown. The chuck 750 may utilize a first jaw member 718 and asecond jaw member 720 as described above. Also, the chuck 750 mayinclude an engagement control member 706 that includes cam surfaces 730and 732 to engage the follower portions 734 and 736 to move the jawmembers 718 and 720 radially away from the work axis 16 as describedabove. However, the manner in which the engagement control member 706 isrotated may differ from that described above. In this regard, the chuck750 may provide a means for engagement and disengagement of theorthopedic implant that is more ergonomic and provides easier movementto control the engagement and disengagement.

Specifically, the chuck 750 may include a lever handle 740 that isconnected to the chuck body 702 via a pivot 742. A fork 744 extends onan opposite side of the pivot 742 from the lever handle 740. The fork744 may engage pins 746 that couple the fork 744 to a control ring 748.In this regard, the chuck body 702 comprises slots 752 that accommodatesmovement of the control ring 748 distally and proximally in a directionalong the working axis 16. Accordingly, movement of the lever handle 740distally and proximally controls the movement of the control ring 748distally and proximally along a direction corresponding to the workingaxis 16. Specifically, proximal movement of the lever handle 740 (i.e.,in a direction toward the engagement portion 704) may result in distalmovement of the control ring 748.

With further reference to FIG. 34, which shows only the control ring748, chuck drive shaft 722, and engagement control member 706, uponadvancement of the control ring 748 distally, the pins 746 engaged withthe control ring 748 may engage opposing notches 754 on the chuck driveshaft 722. This may result in rotationally locking of the chuck driveshaft 722.

Further distal advancement of the control ring 746 relative to theengagement control member 706 may result in a projection 756 on thecontrol ring 746 engaging the engagement control member 706.Specifically, the projection 756 may comprise at least one cam surface760 that contacts a corresponding ramped surface 762 of the control ring706. The cam surface 760 may be arranged relative to the engagementcontrol member 706 such that distal motion of the control ring 706(e.g., under the influence of the lever handle 704) may cause thecontrol member 706 to rotate about the working axis 16 so as to engagethe jaw members 718 and 720 to move the jaw members 718 and 720 awayfrom the working axis 16 as described above. As such, proximal movementof the lever handle 706 may result in distal movement of the controlring 706. This distal movement of the control ring 706 may result in thepins 746 being engaged with the notches 754 on the chuck drive shaft 722to rotationally lock the drive shaft 722. The distal movement may alsoengage the projection 756 such that the cam surface 760 engages theramped surface 762 of the engagement control member 706 to rotate theengagement control member 706 to move the jaw members 718 and 720. Uponrelease of the lever handle 704, the engagement control member 706 mayreturn under the bias of the biasing member 728 as described above.Furthermore, the lever handle 704 may be engaged with biasing members764 at the pivot 742 to return the lever handle 704 to a distal positionso as to disengage the pins 746 from the notches 754 to release thechuck drive shaft 722 to allow rotation thereof.

With further reference to FIGS. 36A and 36B, a controller 146 is shownthat may be utilized with the instrument 10. Specifically, as describedabove, the instrument 10 may have a displacement sensor 42 foroutputting a signal indicative of the relative displacement of a workingportion (e.g., a leading edge 10 a of an orthopedic implant 62). Also,the instrument 10 may have a force sensor 50 for measurement of theforce acting on the working portion (e.g., orthopedic implant 62)axially along the working axis 16. The instrument 10 may include atelemetry cable 174 in operative communication with the displacementsensor 42 and the force sensor 50. The telemetry cable 174 may have aconnector 172 that may interface with a data port 170 of the controller146. While a telemetry cable 174 is shown for interfacing with thecontroller 146, other approaches are possible for relay of data from theinstrument 10 to a controller 146 such as, for example, by way ofwireless telemetry via a wireless protocol such as Bluetooth, IEEE802.11, or the like. Furthermore, the controller 146 may not be aseparate unit, but may be integrated into the instrument 10.

As depicted, the controller 146 may include a touchscreen interface 152for use by a user to interface with the controller 146. The interface146 may allow a user to set a diameter of the working portion (e.g.,orthopedic implant 62) at a diameter selection 160. Moreover, therotational speed of the instrument may be displayed and/or controlled atthe speed selection 162. An operation mode may be selected or input atthe mode selection 150 as will be described in greater detail below.Also, the instrument direction may be selected or input at the directionselection 164. In an embodiment, the instrument 10 may measure a depthof a bore. This may be output in the length measurement output 166.Also, the controller 146 may have a reset selection 153 to allow forresetting the instrument (e.g., for establishing a reference point forthe displacement sensor 42 and/or calibrating the force sensor 50).While a reset selection 153 may be provided on the controller 146, thereset selection 153 may be triggered by use of a first trigger 90 and asecond trigger 92 of the instrument 10. For instance, in normaloperation, actuation of the first trigger 90 may result in operation ofthe instrument 10 in a first direction (e.g., clockwise relative to theworking axis 16). Actuation of the second trigger 92 may result inoperation of the instrument 10 in an opposite direction (e.g.,anticlockwise relative to the working axis 16). Actuation of the firsttrigger 90 at the same time as the second trigger 92 may send a resetsignal to the controller 146 to zero a depth measurement (e.g., toestablish a reference point). Actuation of the first trigger 90simultaneously with the second trigger 92 may also sequence thecontroller 146 (e.g., to indicate a new bore or implant is to beutilized). The controller 146 may also display administrative data 168(e.g., regarding an operation, patient, instrument status information,etc.).

In an embodiment, the controller 146 may determine that an implant 62 isreleased such that the instrument 10 is withdrawn distally relative tothe implant 62. For example, the instrument 10 may be equipped with asensor to detect disengagement of the orthopedic implant 62. Forinstance, a wired or wireless sensor may be disposed in the chuck suchthat the sensor may detect when various components of the chuck are in aposition to disengage an orthopedic implant. Such a sensor may providean output to the controller. Additionally or alternatively, thecontroller 146 may include a selection for input of an indication thatthe orthopedic implant 62 is released. In any regard, upon release andretraction of the instrument 10 from the orthopedic implant 62, anymeasured relative displacement may be ignored (e.g., so as not toaccount for advancement or retraction of the orthopedic implant from thesubstrate into which it is advanced). In this regard, upon reengagementof the implant 62, further advancement may be accurately measured by thedisplacement sensor 42. The spacing of the indexing features 66 may besuch that adjacent indexing features 66 are located nearer to each otherthan the measureable distance of the displacement sensor 42 such thatthe displacement sensor may accurately measure any subsequentadvancement of the implant 62 upon being reengaged after withdrawing theinstrument 10 distally upon disengagement.

As mentioned briefly above, the controller 146 may be configured toperform in various different modes using the mode selection 150. As anexample, the different modes of operation may correspond with differentrelative placements of the leading edge 10 a of the orthopedic implant62 relative to the anatomy of a patient. Different placements of anorthopedic implant are depicted in FIGS. 37, 38, 39, and 40. Forinstance, a bicortical bone cross-section such as those depicted inFIGS. 37-40 may include a hard outer cortex that surrounds a medullarylayer 102. In this regard, in bicortical operation is depicted in FIG.37, the leading edge 10 a of the orthopedic implant 62 may be advancedthrough a first portion of the hard outer cortex 100 a, the medullarylayer 102, and a second portion of the hard outer cortex 100 b. In turn,when the leading edge 10 a breaches the exterior of the second portionof the hard outer cortex 100 b, the instrument 100 may be arrested suchthat the orthopedic implant 62 is placed as depicted in FIG. 37 wherethe leading edge 10 a just breaches the entire bicortical length of thebone. Bicortical operation of the instrument 10 is generally describedin U.S. Pat. No. 6,665,948 which is incorporated by reference herein.

FIG. 38 depicts another mode of operation corresponding to subchondralplacement of the orthopedic implant 62. In this regard, the leading edge10 a of the orthopedic implant 62 is advanced through the first portionof hard outer cortex 100 a, the medullary layer 102, and a portion ofthe second portion of hard outer cortex 100 b. In this regard, theinstrument 10 may be arrested when the leading edge 10 a is embedded inthe second portion of hard outer cortex 100 b as shown in FIG. 38.

FIG. 39 depicts another mode of operation corresponding to an endostealplacement of the orthopedic implant 62. In this regard, the leading edge10 a may be advanced through the first portion of hard outer cortex 100a and through the medullary layer 102. The instrument 10 may be arrestedwhen the leading edge 10 a reaches the second portion of hard outercortex 100 b such that the leading edge 10 a is disposed at theinterface of the medullary layer 102 and the second portion of hardouter cortex 100 b.

FIG. 40 depicts another mode of operation corresponding tomulti-cortical placement of the orthopedic implant 62. In this mode, theleading edge 10 a of the orthopedic implant 62 is advanced through aplurality of bones 101. In this regard, the number of bones throughwhich the orthopedic implant 62 is to be advanced may be set such thatinstrument 10 is arrested when the leading edge 10 a of the orthopedicimplant 62 breaches the second portion of hard outer cortex 100 b of thelast bone 101 through which the orthopedic implant 62 is to be advanced.Multi-cortical placement of the implant 62 may involve settingoccurrence flags that may at least in part be based on the number ofbones though which the orthopedic implant 62 is to pass. For instance,if two bones are to be drilled through, the fourth occurrence of thepassing of the leading edge 10 a from a first medium into a secondmedium having a lower density may indicate completion of the operation.Also, while a bicortical placement is shown in FIG. 40, themulti-cortical mode may have submodes that allow for bicortical,subchondral, or endosteal placement through multiple bones usingidentification techniques to place the orthopedic implant 62 in the lastbone in the series of bones through which the orthopedic implant 62 isto be advanced. That is, the measurement system 40 may monitorpenetration through n−1 bones where n is the number of the last bone inwhich the orthopedic implant 62 is to be placed. For the nth bone, anyof the following specific techniques may be used for bicortical,subchondral, or endosteal placement of the orthopedic implant 62 in thelast bone.

Any of the foregoing placements may correspond with modes of operationof the instrument 10. For instance, selection of a mode corresponding toany one of the foregoing placements may be utilized by selection via themode selection 150 of the controller 146. As such, when a correspondingone of the modes is selected, the controller 146 may be operative tocontrol operation of the measurement system 40 so as to arrest theinstrument 10 when the leading edge 10 a of the orthopedic implant 62reaches the placement designated for the mode or may output an alarm ortake some other action. In this regard, any one of a variety ofapproaches may be utilized to determine when the orthopedic implant 62reaches the various placements described above. In this regard, variousembodiments of methods are described herein.

For instance, determination of the position of the leading edge 10 a ofthe orthopedic implant 62 relative to the structure of a bone 101 may bedetermined using signals output from force and/or displacement sensorsof a measuring system 40 as described in the '948 Patent incorporated byreference in its entirety above. That is, as the leading edge 10 apasses through the various interfaces of the bone structure 101, theseinterfaces may be detected based on signals from the force sensor 50 anddisplacement sensor 42. For instance, when the leading edge 10 a passesfrom the first portion of hard cortex 100 a to the medullary layer 102,the working portion 16 may experience a decrease in the force sensed bythe force sensor 50 and an increase in acceleration. The decrease in theforce may be determined by taking the derivative of the signal outputfrom the force sensor 50. Specifically, the derivative of the signaloutput from the force sensor 50 may become negative, indicating anegative rate of change of the force applied. Alternatively, a localminimum of a second derivative of the force may be determined thatcorresponds to a reduction in the force acting on the working portion16. For instance, a second derivative of the force signal may be takenand the local minimum of the second derivative of the force signal maybe determined using any appropriate computational approach to determinesuch a state in the force signal. Additionally, taking the secondderivative of the output from the displacement sensor 42 may provide asignal indicative of the acceleration. This technique may also be usedto determine when the working portion 16 passes through the secondportion 100 b of hard cortex 100. This may be the first occurrence of adecrease in force and increase in acceleration in the case ofunicortical operation or the second occurrence in the case of bicorticaloperation.

Moreover, it may be determined when the leading edge 10 a contacts thesecond portion 100 b of cortex 100 after passing through the medullarylayer 102. In this regard, a decrease in acceleration and an increase inforce as measured from the displacement sensor 42 and the force sensor50 may be utilized to determine the second portion 100 b of cortex 100has been contacted for endosteal placement. For subchondral placement, agiven displacement offset from the contacting of the second portion 100b of the cortex 100 may be used to advance the leading edge 10 a of theorthopedic implant 62 partially into the second portion 100 b of cortex100.

Such a context is depicted in FIGS. 41 and 42. FIG. 41 depicts a plot800 of various sensor outputs and/or calculated signals during a normalbicortical pass of a leading edge 10 a of an orthopedic implant 62through a bone 101 of a patient. The plot 800 includes a displacementsignal 802. The displacement signal 802 may be a directly measuredsignal from a displacement sensor 42 of a measurement system 40.Alternatively, the displacement signal 802 may be derived from anothersensor (e.g., as a second integral of a signal from an accelerometer orthe like). The plot 800 also includes a velocity signal 804, which maybe measured directly or derived from a displacement sensor or anaccelerometer. The plot 800 also includes an acceleration signal 806.The acceleration signal 806 may be measured (e.g., using anaccelerometer or the like) or may be derived from the displacementsignal 802 (e.g., as a second derivative of the displacement signal802). As discussed above, the velocity signal 804 may be derived fromeither the displacement signal 802 (e.g., as a first derivative thereof)or from the acceleration signal 806 (e.g., as a first integral thereof).Moreover, FIG. 41 may include a force signal 808 representative of achange in force as measured by a force sensor 50. In this regard, theforce signal 808 may not depict an actual force measure, but rather afirst derivative of actual force. FIG. 42 shows an enlarged portion ofthe plot 800 in a region of interest around the interfaces of thecortices.

As best seen in FIG. 42, the contact between the leading edge 10 a andinterface of the medullary layer 102 and the second portion 100 b ofcortex 100 occurs between 3.05 seconds and 3.1 second in the plot 800 atthe interface 801. This interface 801 coincides with the point at whichthe force signal 808 (representing the first derivative of the measuredforce) experiences a maximum (as may be measured by determining when asecond derivative of the measured force is positive). The interface 801may also coincide with a reduction in the acceleration signal 806. Assuch, when the force signal 808 is at a local maximum that coincideswith the acceleration being negative, the interface 801 may bedetermined.

Additionally, and as described in U.S. patent application Ser. No.14/845,602, incorporated by reference above, placement of the orthopedicimplant 62 may be based solely on a single sensor such as a displacementsensor 42 or an acceleration sensor provided with the measurement system40. In this regard, whether an acceleration sensor or a displacementsensor 42 is used, the resulting single signal may be processed toarrive at a displacement signal, a velocity signal, and an accelerationsignal. In turn, these complimentary signals may be used to determinewhen the leading edge 10 a passed through an interface. For instance, asthe leading edge 10 a passes from the first portion 100 a of hard cortex10 to the medullary layer 102, there may be a simultaneous positivedisplacement, velocity, and acceleration as determined from thedisplacement signal, velocity signal, and acceleration signal. This maybe indicative that the leading edge 10 a has passed from the hard outercortex 100 a to the medullary layer 102. A similar condition may occurat a second occurrence of positive displacement, velocity, andacceleration as the leading edge 10 a passes from the second portion 100b of hard cortex 100 to the medium surrounding the bone 101. As such,the bicortical or unicortical mode may be facilitated whereby either asecond occurrence or a first occurrence, respectively, of positivedisplacement, velocity, and acceleration occur simultaneously.

This approach using a single sensor to arrive at a displacement,velocity, and acceleration may also be used to determine when theleading edge 10 a contacts the second portion 100 b of hard cortex 100for support of an endosteal mode. Specifically, as the leading edge 10 ais advanced through the medullary layer 102, the orthopedic implant 62may experience positive displacement, positive velocity, and a negativeacceleration when the second portion 100 b of hard cortex 100 iscontacted. That is, contact of the leading edge 10 a with the secondportion of hard cortex 100 b may be detected with positive displacement,positive velocity, and negative acceleration. As such, an endosteal modeof operation may be supported using a single sensor for generation of adisplacement signal, velocity signal, and acceleration signal.Furthermore, as described above, subchondral placement of the orthopedicimplant 62 may be facilitated by advancing the leading edge 10 a apredetermined distance beyond detection of the leading edge 10 a passingfrom the medullary layer 102 to the second portion 100 b of hard cortex100. This predetermined distance may be controlled by selection of abone type, a value input by a user, or a calculated value based onmeasured values of the first portion 100 a of hard cortex 100 and/ormedullary layer 102 thickness.

FIGS. 43 and 44 reflect a plot 900 reflecting signals that are measuredor determined utilizing a single displacement or acceleration sensor. InFIG. 43, a displacement signal 802 and a velocity signal 804 may beprovided. Furthermore, a derivative signal 810 representative of thederivative of an acceleration signal may be provided. This signal 810may indicate changes of inflection 814 and 816 where the rate of changeof inflection is “concave down” corresponding with a maximum rate ofchange of positive acceleration. As such, these inflection points 814and 816 may be indicative of the passing of the leading edge 10 a of theorthopedic implant 62 passes from a relatively hard medium to arelatively soft medium. In this regard, inflection point 814 may beindicative of the leading edge 10 a passing from the first portion 100 aof hard cortex 100 to the medullary layer 102 and inflection point 816may be indicative of the passing of the leading edge 10 a passing fromthe second portion 100 b of the cortex 100 into the medium surroundingthe bone 101. Moreover, a local minimum at inflection point 812 of thederivative signal 810 may indicate a maximum deceleration of the leadingedge 10 a indicating contact with the second cortex 100 b. In any ofthese instances, determination of the local minimum and/or maximum ofthe derivative signal 810 may be determined using any signal processingknown in the art. For instance, a further derivative may be taken of thederivative signal 810 for use in determining the local minimums and/ormaximums. This signal would be the second derivative of the accelerationsignal. In turn, the derivative signal 810 may be utilized to determineall three interfaces of interest in a bicortical operation. As such, thederivative signal may be used for bicortical, endosteal, and subchondralmodes.

With further reference to FIG. 44, the inflection point 812 of thederivative signal 810 may coincide with the acceleration signal 808passing through zero (i.e., the acceleration passing from positiveacceleration to negative acceleration). This may not always be true, asdemonstrated in FIG. 44. For example, there is a region 902 in which theacceleration signal 808 passes over the zero axis several timescorresponding with increases and decreases in acceleration. However, theminor changes in acceleration direction may not occur with a largeenough rate of change to be detectable in the derivative signal 810.However, the inflection point 812 in FIG. 44 does indicate the interfacebetween a relatively soft layer and a relatively hard layer as the rateof change (negative) of the acceleration signal 810 is a maximum asreflected in the inflection point 812 of the derivative signal 810. Assuch, a filtering approach may be applied such that a rate of change ofthe acceleration signal 810 may be required to be greater than athreshold value to be used to indicate a detected interface.

As may be appreciated, various ones of the foregoing embodiments ofchucks may be utilized to dispose either a smooth walled orthopedicimplant or an orthopedic implant having a plurality of indexing featuresdisposed along the side wall thereof. In this regard, the distal portionof the orthopedic implant has not been discussed in the foregoingembodiments and can generally be among any of the available distalconfigurations, and to orthopedic implants. However, it is presentlyrecognized that in certain contexts it may be difficult for ameasurement system 40 as described herein to accurately discern theposition of an orthopedic implant as it moves through the variousstructures of a bone of a patient. For instance, small diameterorthopedic implants and/or orthopedic implants that are slowly advancedrelative to the bone may not provide sufficient force, acceleration,and/or other displacement based values sufficient for discerning theplacement of the orthopedic implant.

In this regard, an embodiment of an orthopedic implant is depicted inFIGS. 47-49 that may be utilized to assist in determination of theplacement of an orthopedic implant 850 using a measurement system 40 asdescribed herein. Specifically, the orthopedic implant 850 may have atapered or conical distal tip 852. Specifically, the conical distal tip852 may be a relatively shallow taper. Moreover, the distal tip 852 maybe fluted. The fluting of the distal tip 852 may be a high helix angle.This may increase the resulting forces required to induce movement ofthe orthopedic implant 850 through the bone of the patient, thusassisting in the determination of the forces and/or displacement valuesassociated with the advancement. Furthermore, the orthopedic implant 850may include a relief portion 854 disposed proximally to the distal end852 of the orthopedic implant a 50. The relief portion 854 may include astepped in diameter portion of the orthopedic implant 850. That is, therelief portion 854 may comprise a portion of the orthopedic implanthaving a diameter smaller than that of the remaining portion of theorthopedic implant 850. The relief portion 854 may reduce thermal loadon the orthopedic implant he 50 as it is advanced relative to the boneof the patient. This may assist in reducing trauma to the bone tissuedisposed proximally to the distal end 852 as the orthopedic implant 850is advanced relative to the bone. The orthopedic implant 850 may furtherinclude a helical portion 856 proximal to the relief portion 854. Thehelical portion 854 may include fluted reliefs within the side wall ofthe orthopedic implant 850 and/or threads that extend externally to theside wall of the orthopedic implant 850. In either regard, it has beenfound that the helical portion 856 may be operative to gain purchase ona proximal portion of a cortex of a bone, thus assisting in driving thedistal tip 852 of the orthopedic implant 850 relative to a distalportion of cortex of the bone. That is, the helical portion 854 mayassist in advancing the orthopedic implant 850 distally into the bone ofthe patient.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, such illustration and description isto be considered as exemplary and not restrictive in character. Forexample, certain embodiments described hereinabove may be combinablewith other described embodiments and/or arranged in other ways (e.g.,process elements may be performed in other sequences). Accordingly, itshould be understood that only the preferred embodiment and variantsthereof have been shown and described and that all changes andmodifications that come within the spirit of the invention are desiredto be protected.

1.-43. (canceled)
 44. A method of advancing an orthopedic implant into abone of a patient, comprising: engaging the orthopedic implant with achuck of an instrument to restrict axial movement of the orthopedicimplant relative to the chuck along a working axis of the chuck; firstadvancing the orthopedic implant distally into the bone of the patient afirst distance by imparting rotational motion to the chuck when engagedwith the orthopedic implant; first measuring the first distance using adisplacement sensor of a measurement system associated with theinstrument; releasing the orthopedic implant from the chuck; retractingthe instrument relative to the orthopedic implant in a proximaldirection opposite of the direction of the advancing; reengaging theorthopedic implant with the chuck of the instrument to restrict axialmovement of the orthopedic implant relative to the chuck along a workingaxis of the chuck; and second advancing the orthopedic implant distallyinto the bone of the patient a second distance by imparting rotationalmotion to the chuck; and second measuring the second distance using thedisplacement sensor of the measurement system associated with theinstrument.
 45. The method of claim 44, further comprising: summing thefirst distance and the second distance at the measurement system. 46.The method of claim 45, further comprising: determining that theorthopedic implant is released from the chuck; and disregarding anychange in displacement of the displacement sensor when the orthopedicimplant is released from the chuck.
 47. The method of claim 46, whereina sensor is provided relative to the chuck to determine the orthopedicimplant is released from the chuck.
 48. The method of claim 46, whereinthe determining is based on a user input provided to the measurementsystem.
 49. The method of claim 44, wherein the engaging comprises thechuck engaging the orthopedic implant at a first indexing feature of aplurality of indexing features and the reengaging comprises the chuckengaging the orthopedic implant at a second indexing feature of theplurality of indexing features that is proximal to the first indexingfeature.
 50. The method of claim 49, wherein the engaging occurs inresponse to the first advancing, the reengaging occurs in response tothe second advancing, and the releasing occurs in response to theretracting.
 51. A method of placement of an orthopedic implant relativeto a bone of a patient, comprising: engaging the orthopedic implant witha chuck of an instrument to restrict axial movement of the orthopedicimplant relative to the chuck along a working axis of the chuck;advancing the orthopedic implant distally into the bone of the patientwhile the orthopedic implant is engaged with the chuck by impartingrotational motion to the chuck with a drive engaged with the chuck;measuring at least one characteristic of the advancement of theorthopedic implant relative to the bone; continuously monitoring the atleast one characteristic during the advancing to determine apredetermined placement of a distal end of the orthopedic implant; anddeactivating the drive to cease rotation of the chuck to stop theadvancement of the orthopedic implant when the distal end of theorthopedic implant reaches the predetermined placement as determined bythe continually monitored at least one characteristic; wherein thepredetermined placement is selectable by a user from a bicortical mode,a subchondral mode, an endosteal mode, and a multi-cortical mode. 52.The method of claim 51, wherein the at least one characteristiccomprises a force acting axially on the orthopedic implant and a depthof penetration of the orthopedic implant.
 53. The method of claim 51,wherein the at least one characteristic comprises a depth of penetrationof the orthopedic implant as determined by a displacement sensor thatgenerates a displacement signal.
 54. The method of claim 53, wherein thedisplacement signal is used to generate a velocity signal and anacceleration signal, wherein the predetermined placement is determinedbased on the displacement signal, the velocity signal, and theacceleration signal.
 55. The method of claim 54, wherein thedisplacement signal is used to generate a derivative signal comprising aderivative of an acceleration signal generated using the displacementsignal, wherein the derivative signal is used to determine thepredetermined placement. 56.-61. (canceled)